Wide Band Gap Insulators Research Articles

Assessing the SCAN functional for deep defects and small polarons in wide band gap semiconductors and insulators

Assessing the SCAN functional for deep defects and small polarons in wide band gap semiconductors and insulators

First-principles investigations for the structural, optoelectronic and hydrogen storage properties of double perovskite KNaMg2F6-xHx and KNaAe2H6(Ae=Be, Mg, Ca)

In order to search for good hydrogen storage materials, the structural, optoelectronic and hydrogen storage properties of double perovskites KNaMg2F6-xHx and KNaAe2H6(Ae = Be, Mg, Ca) have been studied by first-principles calculations based on density functional theory in this paper. All the negative formation energies demonstrate the thermodynamic stability of these materials. Except for KNaBe2H6, the rest of the materials are wide-band gap semiconductors or insulators. The gravimetric storage capacity of KNaMg2F6-xHx increases with the introduction of hydrogen and reaches a maximum of 5.19 wt% at x = 6. Meanwhile, the KNaBe2H6 exhibits the best storage capacity of 8.57%. The favorable desorption temperature for stable KNaMg2H6 material is 470.4 K, which is feasible in actual application. As the concentration of hydrogen increases, the electronic bandgap of KNaMg2F6-xHx decreases gradually due to its electron conduction band moving to a lower energy range. The bond population analysis indicates that there is a mixture of ionic and covalent bonds in the studied materials. These materials are all ultraviolet absorber, and a red-shift can be observed in the absorption edge due to the variation of bandgap.

Physics of band-filling correction in defect calculations of solid-state materials.

In solid-state physics/chemistry, a precise understanding of defect formation and its impact on the electronic properties of wide-bandgap insulators is a cornerstone of modern semiconductor technology. However, complexities arise in the electronic structure theory of defect formation when the latter triggers partial occupation of the conduction/valence band, necessitating accurate post-process correction to the energy calculations. Herein, we dissect these complexities, focusing specifically on the post-process band-filling corrections, a crucial element that often demands thorough treatment in defect formation studies. We recognize the importance of these corrections in maintaining the accuracy of electronic properties predictions in wide-bandgap insulators and their role in reinforcing the importance of a reliable common reference state for defect formation energy calculations. We explored solutions such as aligning deep states and electrostatic potentials, both of which have been used in previous works, showing the effect of band alignment on defect formation energy. Our findings demonstrate that the impact of defect formation on electronic structure (even deep states) can be significantly dependent on the supercell size. We also show that within band-filling calculations, one needs to account for the possible change of electronic structure induced by defect formation, which requires sufficient convergence of electronic structure with supercell size. Thus, this work emphasizes the critical steps to accurately predict defect formation energy and paves the way for future research to overcome these challenges and advance the field with more efficient and reliable predictive models.

All electron GW with linearized augmented plane waves for metals and semiconductors

GW approximation is one of the most popular parameter-free many-body methods that go beyond the limitations of the standard density functional theory (DFT) to determine the excitation spectra for moderately correlated materials and in particular the semiconductors. It is also the first step in developing the diagrammatic Monte Carlo method into an electronic structure tool, which would offer a numerically exact solution to the solid-state problem. While most electronic structure packages offer support for GW calculations for band-insulating materials, the level of support for metallic systems is somewhat limited. This limitation can be partly attributed to the relatively minor differences often observed between GW and DFT results in treating metallic systems, which is not expected to persist to higher orders in perturbation theory. Describing metals within the GW framework presents a challenge, as it requires accurate resolution of Fermi surface singularities, which, in turn, calls for a dense momentum mesh. Here we implement the GW algorithm within the all-electron Linear Augmented Plane Wave framework, where we pay special attention to the metallic systems, the convergence with respect to momentum mesh, and proper treatment of the deep laying core states, as needed for the future variational diagrammatic Monte Carlo implementation. Our improved algorithm for resolving Fermi surface singularities allows us a stable and accurate analytic continuation of imaginary axis data, which is carried out for GW excitation spectra throughout the Brillouin zone in both the metallic and insulating materials and is compared to numerically more stable contour deformation integration technique. We compute band structures for elemental metallic systems Li, Na, and Mg as well as for various narrow and wide bandgap insulators such as Si, BN, SiC, MgO, LiF, ZnS, and CdS and compare our results with previous GW calculations and available experiments data. Our results are in good agreement with the available literature. Thus our software allows users to compute full bandstructures for metals and insulators using all-electron potential without downfolding to Wannier orbital basis.

Optical properties and electronic structures of intrinsic gapped metals: Inverse materials design principles for transparent conductors

Traditional solid-state physics has long correlated the optical properties of materials with their electronic structures. However, recent discoveries of intrinsic gapped metals have challenged this classical view. Gapped metals possess electronic properties distinct from both metals and insulators, with a large concentration of free carriers without any intentional doping and an internal bandgap. This unique electronic structure makes gapped metals potentially superior to materials designed by intentional doping of the wide bandgap insulators. Despite their promising applications, such as transparent conductors, designing gapped metals for specific purposes remains challenging due to the lack of understanding of the correlation between their electronic band structures and optical properties. This study focuses on representative examples of gapped metals and demonstrates the cases of (i) gapped metals (e.g., CaN2) with strong intraband absorption in the visible range, (ii) gapped metals (e.g., SrNbO3) with strong interband absorption in the visible range, and (iii) gapped metals (e.g., Sr5Nb5O17) that are potential transparent conductors. We explore the complexity of identifying potential gapped metals for transparent conductors and propose inverse materials design principles for discovering next-generation transparent conductors.

Optical Second Harmonic Generation on LaAlO3/SrTiO3 Interfaces: A Review.

As we approach the limits of semiconductor technology, the development of new materials and technologies for the new era in electronics is compelling. Among others, perovskite oxide hetero-structures are anticipated to be the best candidates. As in the case of semiconductors, the interface between two given materials can have, and often has, very different properties, compared to the corresponding bulk compounds. Perovskite oxides show spectacular interfacial properties due to the the rearrangement of charges, spins, orbitals and the lattice structure itself, at the interface. Lanthanum aluminate and Strontium titanate hetero-structures (LaAlO3/SrTiO3) can be regarded as a prototype of this wider class of interfaces. Both bulk compounds are plain and (relatively) simple wide-bandgap insulators. Despite this, a conductive two-dimensional electron gas (2DEG) is formed right at the interface when a LaAlO3 thickness of n≥4 unit cells is deposited on a SrTiO3 substrate. The 2DEG is quite thin, being confined in only one or at least very few mono-layers at the interface, on the SrTiO3 side. A very intense and long-lasting study was triggered by this surprising discovery. Many questions regarding the origin and characteristics of the two-dimensional electron gas have been (partially) addressed, others are still open. In particular, this includes the interfacial electronic band structure, the transverse plane spatial homogeneity of the samples and the ultrafast dynamics of the confined carriers. Among a very long list of experimental techniques which have been exploited to study these types of interfaces (ARPES, XPS, AFM, PFM, …and many others), optical Second Harmonic Generation (SHG) was found to be suitable for investigating these types of buried interfaces, thanks to its extreme and selective interface-only sensitivity. The SHG technique has made its contribution to the research in this field in a variety of different and important aspects. In this work we will give a bird's eye view of the currently available research on this topic and try to sketch out its future perspectives.

Mesoscopic 2D molecular self-assembly on an insulator

Two-dimensional (2D) nanostructures and nanomaterials offer potential for a wide range of technological applications in electronics, optoelectronics, data storage, sensing and catalysis. On-surface molecular self-assembly—where organic molecules act as building blocks and where surfaces play the role of supporting templates—allows for the bottom-up synthesis of such 2D systems with tuneable atomically precise morphologies and tailored electronic properties. These self-assembly protocols are well established on metal surfaces, but remain limited on electronically gapped substrates (insulators, semiconductors). The latter are useful for preventing electronic coupling (that is, hybridization between molecular assembly and underlying surface) and for avoiding quenching of optical processes, necessary for prospective electronic and optoelectronic applications. In particular, molecular self-assembly on surfaces other than weakly interacting metals can be challenging due to substrate reactivity, defects and inhomogeneities, resulting in intricate energy landscapes that limit the growth kinetically and hampers the synthesis of large-area defect-free 2D systems. Here, we demonstrate the self-assembly of a 2D, atomically thin organic molecular film on a model wide bandgap 2D insulator, single-layer hexagonal boron nitride (hBN) on Cu(111). The molecular film consists of flat, aromatic 9,10-di-cyano-anthracene (DCA) molecules. Our low-temperature scanning tunnelling microscopy and spectroscopy measurements revealed mesoscopic (>100 × 100 nm2), topographically homogeneous crystalline molecular domains resulting from flat molecular adsorption and noncovalent in-plane cyano-ring bonding, with electronically decoupled molecular orbitals (MOs) lying within the hBN electronic gap. These MOs exhibit an energy level spatial modulation (∼300 meV) that follows the moiré work function variation of hBN on Cu(111). These findings pave the way for large-area, atomically precise, highly crystalline 2D organic (and metal-organic) nanomaterials on electronically functional wide bandgap insulators.

Discovering Superhard B-N-O Compounds by Iterative Machine Learning and Evolutionary Structure Predictions.

We searched for new superhard B–N–O compounds with an iterative machine learning (ML) procedure, where ML models are trained using sample crystal structures from an evolutionary algorithm. We first used cohesive energy to evaluate the thermodynamic stability of varying BxNyOz compositions and then gradually focused on compositional regions with high cohesive energy and high hardness. The results converged quickly after a few iterations. Our resulting ML models show that Bx+2NxO3 compounds with x ≥ 3 (like B5N3O3, B6N4O3, etc.) are potentially superhard and thermodynamically favorable. Our meta-GGA density functional theory calculations indicate that these materials are also wide bandgap (≥4.4 eV) insulators, with the valence band maximum related to the p-orbitals of nitrogen atoms near vacant sites. This study demonstrates that an iterative method combining ML and ab initio simulations provides a powerful tool for discovering novel materials.

First-principles modeling of conductivity at the (001), (110), and (111) SrTiO3/LaAlO3 heterointerfaces

The complex polar oxide heterojunction of ${\mathrm{SrTiO}}_{3}/{\mathrm{LaAlO}}_{3}$ (STO/LAO) is of great interest due to the emergent physical phenomena observed at the interface. STO and LAO separately are wide band-gap insulators. However, upon joining them at the 001, 110, and 111 crystallographic planes, the interface undergoes a transition to a conductive state. Although first-principles modeling of the 001 plane interface has been widely studied, there is a lack of reports regarding the 110 and 111. This paper expands the theoretical model of the STO/LAO heterointerface to the three crystallographic planes (001, 110, and 111) where the conductivity has been experimentally reported. The calculations showed that whereas at the 001 interface the conductivity appears at a critical thickness of 4 monolayers of LAO, the 110 and 111 planes have no clear critical thickness; these two interfaces were always conductive. Nevertheless, the number of conductive electrons per unit cell increases with the thickness of the LAO layer in the 110 and 111 interfaces. This is related to the energy levels downshifting due to the electrostatic potential buildup (which was in the opposite direction respect to the 001 interface), increasing the number of conductive sates below the Fermi level. Given the absence of a critical thickness and the fact that chemical intermixing and oxygen vacancies at the interface were not considered, the main mechanism responsible for the conductivity in the 110 and 111 planes was attributed to the large structure reconstruction that locally changes the energy levels at the interface causing charge transfer and accumulation at the layers close to the interface.

Comparative study of electronic structure, optical properties, lattice dynamics and thermal expansion behaviour of energetic ammonium and potassium dinitramide salts

In this work, we present a detailed first principles study addressing the electronic structure, optical properties, lattice dynamics and thermal expansion studies of energetic salts ammonium dinitramide (ADN) and potassium dinitramide (KDN). From the electronic structure, it is vivid that both the compounds are wide band gap insulators with an indirect band gap of value of 4.3 eV for KDN. Optical constants reveal that ADN and KDN possess considerable optical anisotropy. Analysis of the vibrational modes reveal that the N(NO2) group contributions are considerably large in the high-frequency region in KDN. Phonon dispersion relations computed within the harmonic approximation unambiguously shows that both the compounds are dynamically stable in the reported monoclinic structure. In addition, the optical and acoustical modes are highly interactive as evident from the dispersion spectra, which might lead to low thermal conductivity, quite desirable for an energetic material. Thermal expansion studies within the quasi-harmonic approximation reveal a large positive thermal expansion in both the compounds with KDN having relatively larger thermal expansion coefficient when compared to ADN, in agreement with experiments.

Optically stimulated luminescence decay and dosimetric properties of cerium-doped potassium sulfate phosphor.

Optically stimulated luminescence (OSL) is used for dating in archaeology and geology, and in dosimetry of ionizing radiation. Some crystalline wide band-gap insulators may be used as OSL radiation detectors. Recently it was found that cerium-doped potassium sulfate crystals have promising luminescence properties. This paper presents some OSL properties of K2 SO4 :Ce crystals that were prepared in the form of pellets. The crystals exhibited a strong luminescence signal, good measurement repeatability, and high sensitivity for ionizing radiation. Best results were obtained after annealing at 1000°C. Dose-dependence characteristics were determined in the range 10 mGy to 11.2 Gy. OSL decay curves consisted of several components. Fast and slow OSL components of the phosphor had different properties. The slow component was quite stable and obeyed power law dependence. It decayed in the 55 days after irradiation. Its luminescence properties depended on sample preparation and the storage time after irradiation.

Nanopatterning of Weak Links in Superconducting Oxide Interfaces.

The interface between two wide band-gap insulators, LaAlO and SrTiO (LAO/STO), hosts a quasi-two-dimensional electron gas (q2DEG), two-dimensional superconductivity, ferromagnetism, and giant Rashba spin-orbit coupling. The co-existence of two-dimensional superconductivity with gate-tunable spin-orbit coupling and multiband occupation is of particular interest for the realization of unconventional superconducting pairing. To investigate the symmetry of the superconducting order parameter, phase sensitive measurements of the Josephson effect are required. We describe an approach for the fabrication of artificial superconducting weak links at the LAO/STO interface using direct high-resolution electron beam lithography and low-energy argon ion beam irradiation. The method does not require lift-off steps or sacrificial layers. Therefore, resolution is only limited by the electron beam lithography and pattern transfer. We have realized superconducting weak links with a barrier thickness of 30–100 nm. The barrier transparency of the weak links can be controlled by the irradiation dose and further tuned by a gate voltage. Our results open up new possibilities for the realization of quantum devices in oxide interfaces.

First-principles investigation of mechanical, electronic and optical properties of H-, F- and Cl-diamane

Most recently, fluorinated diamond monolayer so called “F-diamane” has been successfully experimentally realized via fluorination of bilayer-graphene (Nat. Nanotechnol. 15 (2020), 59–66). Motivated by this experimental advance, we conduct density functional theory simulations to explore the stability, mechanical, electronic and optical properties of diamane nanosheets. In this work we consider diamane nanosheets functionalized with H, F and Cl atoms. We particularly examine thickness effect on the properties of functionalized diamane nanomembranes. According to phonon dispersions and ab-initio molecular dynamics results, thermal and dynamical stability of studied systems are confirmed. It is found that by increasing the number of carbon layers in diamane the elastic modulus and tensile strength increase. Analysis of electronic band-structures reveal that while H- and F-diamane are wide band gap semiconductors and insulators, respectively, Cl-diamanes are direct band gap semiconductors, highly promising for nanoelectronics applications. Optical calculations show that Cl-diamane can absorb the visible light whereas H and F counterparts absorb ultraviolet range of light. First-principle results by this study provide a comprehensive vision on the thickness dependent mechanical, electronic and optical responses of functionalized diamane nanosheets and can serve as a useful guide for future studies.

Reconciliation of Differences in Apparent Diffusion Coefficients Measured for Self-Exchange Electron Transfer between Molecules Anchored to Mesoporous Titanium Dioxide Thin Films.

Redox-active sites present at large concentrations as part of a solid support or dissolved as molecules in fluid solutions undergo reversible self-exchange electron-transfer reactions. These processes can be monitored using a variety of techniques. Chronoamperometry and cyclic voltammetry are common techniques used to interrogate this behavior for molecules bound to mesoporous thin films of wide-bandgap semiconductors and insulators. In order to use these techniques to obtain accurate values for apparent diffusion coefficients, which are proxies for rate constants for self-exchange electron transfer, it is imperative to take into consideration nonidealities in redox titrations, parasitic currents, and ohmic resistances. Using spectroelectrochemical measurements taken concurrently with measurements of chronoamperometry data, we show that the spectroscopic data is not confounded from effects of parasitic currents or electroinactive dyes. However, we show that the thickness of the thin film over the region that is optically probed by the measurements must be known. When each of these considerations is included in data analyses, calculated apparent diffusion coefficients are, within error, independent of the method used to obtain the data. These considerations help reconcile variations in apparent diffusion coefficients measured using different techniques that have been reported over the past several decades and allow correct analyses to be performed in the future, independent of the method used to obtain the data.

LaScO3/SrTiO3: A conducting polar heterointerface of two 3d band insulating perovskites

This work reports a quasi-two-dimensional electron gas (q-2DEG) system at the interface of two wideband-gap insulators, (TiO2-terminated) SrTiO3 and LaScO3, with a minimum thickness of 4-unit cell (uc). The highly crystalline and abrupt heterointerface is confirmed with high-resolution electron microscopy. The mixed Ti4+ and Ti3+ valence states (for 4 uc of LaScO3) obtained from the x-ray photoelectron spectroscopy study suggest an intrinsic electronic reconstruction at the interface, leading to a metallic nature. This origin is well supported by density functional theory calculations that reveal an emergence of 3.3 states/eV/spin at the Fermi level for 4 uc in accordance with the polar catastrophe model. The study offers one more perovskite heterostructure, like LaAlO3/SrTiO3, for unraveling the q-2DEG phenomena toward a clear mechanism and futuristic applications.

Charge Transport in Alkali-Metal Superoxides: A Systematic First-Principles Study

Charge-transport mechanisms within the discharge products of alkali-metal/O2 batteries can strongly influence the performance of these systems. To date, discharge products comprising alkali peroxides (Li2O2 and Na2O2) and superoxides (LiO2, NaO2, and KO2) have been observed. In general, cells that discharge to a superoxide exhibit lower overpotentials than those that form the corresponding peroxide. These lower overpotentials have been hypothesized to originate from more efficient charge transport within the superoxides. While the transport mechanisms in the peroxides have been well studied, consensus regarding the intrinsic conductivity across the alkali-metal superoxides is lacking. Here, we present a systematic first-principles study of charge-transport mechanisms across the alkali-metal (Li, Na, K) superoxides. Our study draws on our prior investigations of the alkali peroxides and of sodium superoxide, while adding new analyses for lithium and potassium superoxides (LiO2 and KO2). In the case of KO2, a nonsymmetrized room-temperature structure is proposed to account for a dynamic Jahn–Teller effect. Band gaps, equilibrium (charged) defect concentrations, mobilities, and intrinsic conductivities are estimated for both LiO2 and KO2. Overall, the alkali superoxides are predicted to be wide band gap insulators, with gaps exceeding 4 eV. These large band gaps imply that negligible transport occurs via band conduction. Compared to the alkali peroxides, ionic conductivities in the superoxides are predicted to be 8–11 orders of magnitude larger, ranging from 4 × 10–9 to 5 × 10–12 S/cm at room temperature. Regarding electronic conductivities, transport in NaO2 and KO2 is predicted to occur via polaron hopping, with low conductivities on the order of 10–19 to 10–20 S/cm. These values are similar to what has been previously reported for the peroxides. Importantly, the present calculations indicate that LiO2 has a much larger electronic conductivity (also arising from polaron hopping) than its Na and K analogues, 9 × 10–12 S/cm at 300 K. These data suggest that the low overpotentials observed for Na- and KO2-based batteries cannot be explained by high intrinsic electronic conductivities. In contrast, the much larger conductivities predicted for LiO2 imply that the superior performance observed in LiO2-based cells may reflect the ability of LiO2 to support higher charge-transport rates.

Computational screening of bulk materials with intrinsic intermediate band

Intermediate band compounds are promising high-efficiency materials for solar cells. Besides that, they also show unusual properties that make them interesting from a fundamental point of view. In this work, we create a series of filters capable of searching the AFLOW-ICSD materials database for compounds that show intrinsic intermediate bands. We analyse all available binary and ternary compounds, totaling 45,656 entries. The selected materials show at least one narrow band (maximum width of 1 eV) next to the energy gap. After removal of repeated entries and of wide bandgap insulators, we end up with a total of 660 materials that present intermediate bands. From this group, the majority has completely empty or filled intermediate bands or, during new calculations, changed to another state with a different type of intermediate band or no band of this type. Nevertheless, three compounds fulfill all criteria and continue to present a partially filled intermediate band (Bi2Rh2O7, Ca5FeN6, and OsTb6I10), showing potential for solar cells applications.

(Invited) Gate Stack Technology for Advanced GaN-Based Mos Devices

GaN-based power devices have received much attention for their application in the next-generation high-frequency and high-power devices. Recently, AlGaN/GaN heterojunction field-effect transistors (HFETs) with Schottky gate structures have been implemented into modern wireless communication systems. However, their applications are restricted because of large gate leakage current through the Schottky contacts and their normally-on operation. To overcome these limitations, MOS gate stacks on GaN-based materials have been intensively studied. Moreover, normally-off vertical power MOSFETs on free-standing GaN substrates have become a hot topic in power electronics. In contrast with the Si-based semiconductors, deposition of wide bandgap insulators on the AlGaN and GaN surfaces is thought to be a plausible method for fabricating MOS gate stacks. Among the various insulating materials, Al2O3 and SiO2 exhibit a sufficiently wide bandgap and thermal stability for MOS device applications. However, it is well known that Al2O3 involves an essential problem of electron trapping, thus leading to significant Id-Vg hysteresis and Vth instability. In addition, poor electrical properties of GaN-based MOS devices have been reported even for the well-established ALD-Al2O3 and CVD-SiO2 films. We have investigated suitable insulating materials and deposition methods for AlGaN/GaN MOS-HFETs and GaN-MOSFETs. This paper reviews our recent findings on gate stack engineering for advanced GaN-based MOS devices and discusses a common guiding principle to improve device performance and reliability. We implemented nitrogen incorporated Al2O3 (AlON) gate dielectrics into the AlGaN/GaN MOS-HFETs and successfully improved the performance and reliability of the devices. Our physical and electrical characterizations revealed superior thermal stability of the AlON/AlGaN interface and the importance of conducting dielectric deposition under a reactive nitric atmosphere to suppress intermixing at the interface. Recently, we demonstrated high current and high voltage (20A/730V) normally-off AlGaN/GaN MOS-HFETs with the AlON gate dielectrics. For fabricating GaN-MOS structures, oxidation of the GaN surface is a fundamental method of obtaining gate insulators, but severe drawbacks, such as insufficient conduction band offset at GaOx/GaN interfaces and rough surface morphology have been pointed out. Thus, we proposed GaN-MOS structures with thin GaOx interlayers, in which oxide interlayers were formed by oxidation of GaN surface prior to SiO2 deposition. We also found that high-quality SiO2/GaOx/GaN stacked structures were formed by optimizing conditions for plasma-enhanced CVD of SiO2 films. Consequently, well-behaved C-V curves with negligible hysteresis and frequency dispersion were obtained. Moreover, an extremely low interface state density (< 1010 cm-2eV-1) and an improved reliability in terms of reproducibility and robustness against dielectric breakdown were achieved by rapid thermal annealing of SiO2/GaOx/GaN MOS devices.

Wideband luminescence from bandgap-matched Mg-based Si core-shell geometry nanocomposite

We use wet treatment to integrate red-luminescent Si nanoparticles with Mg-based wide-bandgap insulators Mg(OH) and MgO (5.7 and 7.3 eV respectively). In the process, Mg2+ is reduced on Si nanoparticle clusters, while suffering combustion in water, producing a spatially inhomogeneous Mg(OH)2/MgO-Si nanoparticle composite with an inner material predominantly made of Si, and a coating consisting predominantly of magnesium and oxygen (“core-shell” geometry). The nanocomposite exhibit luminescence covering nearly entire visible range. Results are consistent with formation of Mg(OH)2/MgO phase with direct 3.43-eV bandgap matching that of Si, with in-gap blue-green emitting states of charged Mg and O vacancies. Bandgap match with nanocomposite architecture affords strong enough coupling for the materials to nearly act as a single hybrid material with novel luminescence for photonic and photovoltaic applications.

Role of Hydrogen Abstraction Reaction in Photocatalytic Decomposition of High Energy Density Materials

Explosive phenomena includes a stunningly wide range of diverse manifestations, such as supernova remnant shocks and solar flares, violent decomposition chemistry and synthesis of superior materials under extreme conditions, weapons, missiles, and high velocity impact damage, fuels for space rocket motors, festive fireworks, and applications of detonation waves in construction industry and shocks in medicine. With earliest stages of explosive chemistry in energetic materials remaining poorly understood and constantly posing new science questions, an achievement of a controllable initiation of detonation process represents a particular challenge. Precise tuning of sensitivity to initiation of detonation via photo-excitation appears unreachable because all known secondary explosives are wide band gap insulators. This research demonstrates how YAG:Nd laser irradiation triggers explosive decomposition of PQ-PETN composites formed by pentaerythritol tetranitrate (PETN), high energy density material, mixed with...