Effective Carrier Lifetime Research Articles

Optimization of Silicon Heterojunction Interface Passivation on p‐ and n‐Type Wafers Using Optical Emission Spectroscopy

To increase the efficiency in p‐type wafer‐based silicon heterojunction (SHJ) technology, one of the most crucial challenges is the achievement of excellent surface passivation. Herein, chemical passivation techniques known for n‐type technology are successfully applied on p‐type float–zone (FZ) wafers, and wafer surface passivation quality is correlated with parameters from plasma diagnostics, namely crystallization rate and electron temperature indices. It is shown that plasma ignition at higher powers than deposition powers enhances effective minority carrier lifetimes τeff fourfold for p‐ (0.6–2.1 ms) and sixfold for n‐type (0.6–3.2 ms) wafers while giving opportunity to process under lower electron temperature indices during the nucleation phase. A subsequent hydrogen plasma treatment has a further beneficial effect on chemical passivation, leading to high effective minority carrier lifetimes of 4.5 and 3.1 ms, and implies open‐circuit voltages, i‐VOC, of 735 and 720 mV for p‐ and n‐type wafers, respectively. In particular, cell precursors built on p‐type wafers demonstrate excellent surface passivation with τeff and i‐VOC (4.1 ms and 745 mV). Using these process optimizations, SHJ cells on both p‐ and n‐type wafers are fabricated with efficiencies exceeding 21%.

Room Temperature Enhancement of Electronic Materials by Superacid Analogues.

Treatment with the superacid bis(trifluoromethanesulfonyl)amide (sometimes known as TFSA, TFSI, or HNTf2) enhances the properties of a wide range of optoelectronic materials, resulting in longer effective carrier lifetimes and higher photoluminescence quantum yields. We have conducted a multimaterial study treating both crystalline silicon and transition metal dichalcogenide (TMDC) monolayers and few-layer flakes with solutions formed from TFSA and a range of compounds with related chemical structures with different Lewis acidities, in order to elucidate the factors underpinning the TFSA-related class of enhancement treatments. We adopt dichloromethane (DCM) as a common solvent as it provides good results at room temperature and is potentially less hazardous than TFSA-dichloroethane (DCE) heated to ∼100 °C, which has been used previously. Kelvin probe experiments on silicon demonstrate that structurally similar chemicals give passivating films with substantially different charge levels, with the higher levels of charge associated with the presence of CF3SO2 groups resulting in longer effective lifetimes due to an enhancement in field-effect passivation. Treatment with all analogue solutions used results in enhanced photoluminescence in MoS2 and WS2 compared to untreated controls. Importantly we find that MoS2 and WS2 can be enhanced by analogues to TFSA that lack sulfonyl groups, meaning an alternative mechanism to that proposed in computational reports for TFSA enhancement must apply.

English

In this manuscript, we present a study on the effects of magnetic field on charge carrier effective lifetime within the base of a polycrystalline PV solar cell p-n junction. This study is elaborated in two forms as a theoretical study and an experimental study. Indeed, under various magnetic field values, PV solar cell is illuminated by using the light from stroboscopic. From a theoretical approach mainly use the open circuit voltage decay method.  Green’s functions and boundaries conditions are used to solve charge carrier’s diffusion equation. Open circuit transient voltage decay expression is found. The charge carriers’ effective lifetime values inversely proportional to the slope of open circuit voltage decay curve are deducted. A simple experimental set-up used open circuit voltage decay method mainly, these experimental measurements of charge carriers’ effective lifetime are done and the effects of magnetic field are then outlined. Globally, magnetic effects on effective charge carrier lifetime are then analyzed. These two types of results obtained present qualitatively the decay of charge carriers’ effective lifetime when magnetic field increase. In the first time, theoretical results and experimental results are in good agreement and in the second time these results are in good agreement with literature results. Key words: Effective lifetime, open circuit voltage decay, magnetic field.

Charge carrier dynamics and photovoltaic properties of near-infrared absorbing squaraine incorporated solution-processed additive-free PTB7:PCBM based ternary solar cells

The introduction of a third component vehemently modifies the morphology and charge carrier dynamics in the blend of a donor–acceptor pair, thereby affecting the photovoltaic properties of organic solar cells (OSCs). Combining steady-state, impedance, and transient spectroscopic measurements, photovoltaic properties of 2,4-bis[4-(N,N-diisobutylamino)-2,6-dihydroxyphenyl] squaraine (SQ) incorporated additive-free PTB7:PC70BM OSCs are assessed. As observed from steady-state measurements, concomitant enhancement in open-circuit voltage (VOC) and short-circuit current density (JSC) has caused a 33% enhancement in power conversion efficiency (PCE) with good reliability and reproducibility. On introducing 25 wt.% SQ to the OSCs, V OC has increased from 0.74 to 0.80 V, while J SC has improved from 11.3 to 13.9 mA cm−2 with an increment in exciton dissociation probability rate from 81.5% to 94.9%. However, the fill factor values show inconsistent marginal variations with SQ addition. Equivalent circuit modeling of bias-voltage dependent impedance spectra along with transient photovoltage measurements reveal an improvement in effective charge carrier lifetime for the SQ incorporated OSCs, in comparison to the binary device. The addition of SQ also ensures better charge transport and extraction, as evidenced by photo-CELIV and transient photocurrent analysis. Atomic force microscopy (AFM) images confirm the effective tuning of the morphology of the active layer when SQ is introduced into the binary blend, favoring efficient charge dissociation and transport. The possible operation mechanism of SQ incorporated ternary OSCs is proposed based on photoluminescence and AFM measurements. Moreover, the un-encapsulated OSC with 25 wt.% SQ has retained 91% of the initial PCE, while for the binary device the PCE declined to ∼75% of the initial value after 200 h of continuous 1 sun illumination from a white LED in ambient atmosphere.

Unveiling charge dynamics of visible light absorbing oxysulfide for efficient overall water splitting

Oxysulfide semiconductor, Y2Ti2O5S2, has recently discovered its exciting potential for visible-light-induced overall water splitting, and therefore, imperatively requires the probing of unknown fundamental charge loss pathways to engineer the photoactivity enhancement. Herein, transient diffuse reflectance spectroscopy measurements are coupled with theoretical calculations to unveil the nanosecond to microsecond time range dynamics of the photogenerated charge carriers. In early nanosecond range, the pump-fluence-dependent decay dynamics of the absorption signal is originated from the bimolecular recombination of mobile charge carriers, in contrast, the power-law decay kinetics in late microsecond range is dominated by hole detrapping from exponential tail trap states of valence band. A well-calibrated theoretical model estimates various efficiency limiting material parameters like recombination rate constant, n-type doping density and tail-states parameters. Compared to metal oxides, longer effective carrier lifetime ~6 ns is demonstrated. Different design routes are proposed to realize efficiency beyond 10% for commercial solar-to-hydrogen production from oxysulfide photocatalysts.

Explore the correlation between intervalley scattering and phonon bottleneck effect on the hot carrier relaxation in bulk GaSb and InN for hot carrier solar cells

Slowed carrier intervalley scattering (IVS) may trap some photo-excited carriers within side valleys and reduce the overall thermalization rate. On the other hand, the thermalization rate could also be significantly retarded within the gamma valley by slowing the Klemens decay due to a large phononic bandgap via the phonon bottleneck effect (PBE). However, the correlation between IVS and PBE on slowing the carrier relaxation rate is still unclear. Herein, high-quality bulk InN and GaSb with similar electronic bandgap but remarkably different phononic structures are studied to clarify the above correlation through picosecond time-resolved photoluminescence. The occurrence of IVS is controlled by using different pump energies at high carrier density (∼1019 cm−3). The relaxations of carriers excited at the band edge just above and far above the side valley threshold are, therefore, studied in GaSb. It shows that the effective hot carrier lifetime (τ1) of GaSb gets significantly extended with higher pump energy mainly due to more carriers being trapped in side valleys through IVS. Nevertheless, the longest τ1 of GaSb is still shorter than the shortest τ1 of InN with a more polar nature and larger phononic bandgap. This implies that PBE plays a more decisive role in retarding Γ valley carrier relaxation than the slowed IVS. It indicates that the large phononic bandgap and Fröhlich coupling constant are keys to the slow thermalization rate if the Fröhlich interaction dominates. If the deformation potential interaction dominates this process, then low side valley threshold energy and the Fröhlich constant determine the reduction of the overall thermalization rate.

Self-assembled multifunctional nanostructures for surface passivation and photon management in silicon photovoltaics

Abstract This work reports the fabrication and characterization of multifunctional, nanostructured passivation layers formed using a self-assembly process that provide both surface passivation and improved light trapping in crystalline silicon photovoltaic (PV) cells. Scalable block copolymer self-assembly and vapor phase infiltration processes are used to form arrays of aluminum oxide nanostructures (Al2O3) on crystalline silicon without substrate etching. The Al2O3 nanostructures are characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and spectroscopic ellipsometry. Injection-level dependent photoconductance measurements are used to determine the effective carrier lifetime of the samples to confirm the nanostructures successfully passivate the Si surface. Finite element method simulations and reflectance measurement show that the nanostructures increase the internal rear reflectance of the PV cell by suppressing the parasitic optical losses in the metal contact. An optimized morphology of the structures is identified for their potential use in PV cells as multifunctional materials providing surface passivation, photon management, and carrier transport pathways.

On the Application of Lifetime-Equivalent Defect Densities on Solar Cell Level

The concept of lifetime-equivalent defect density based on lifetime measurements as a measure of electrically active defect density is extended to solar cells using Suns-V $_{\mathrm{oc}}$ measurements. It is found to be superior to previous approaches, and offers defect-specific injection-dependent information. However, the correct application of the presented method requires some knowledge of or reasonable assumptions on sample properties and measurement conditions, in particular, effective intrinsic carrier concentration, doping level, and measurement temperature. Furthermore, it is found that samples with high effective excess carrier lifetime can be susceptible to nonequilibrium related issues when the measurement duration is too short compared with lifetime. The use of series-resistance affected current-voltage curves is found to be error-prone.

Passivation properties of HfO2-SiO2 mixed metal oxide thin films with low reflectivity on silicon substrates for semiconductor devices

HfO2-SiO2 mixed oxide-based thin films were introduced in this work, and their passivation and anti-reflection properties were examined by using carrier lifetime, x-ray diffraction, scanning electron microscope, energy dispersive x-ray analysis, reflectance, and Fourier transform infrared measurements. The HfO2-SiO2 mixed oxide solutions were prepared with different composition ratios, and the thin films were formed on p-type CZ-Si substrates using the spin-coating technique. Annealing of the samples was carried out in ambient air at different temperatures after optimizing the solution ratio. When annealed at 600 and 700°C, the average reflectance of the samples was observed to be around 15% in the spectral range of 300-1000 nm, with a minimum reflectance point lying in the visible range. The effective carrier lifetimes increased up to 32 μs after annealing at 600°C compared to the initial lifetime of around 2 μs. Annealing at higher temperatures significantly decreased the carrier lifetimes (4.5 and 0.6 μs for 700 and 800°C, respectively). The results of this study revealed that the HfO2-SiO2 mixed oxide films can provide a good passivation effect in addition to an effective anti-reflection property depending on the annealing temperature.

A novel passivating electron contact for high-performance silicon solar cells by ALD Al-doped TiO2

Titanium oxide (TiO2) thin film has attracted wide interest in high-efficiency silicon solar cells as an electron selective contact due to its low conduction band offset with silicon and an excellent level of passivation, while the incorporation of a small amount of dopants is also expected to improve the performance of thin films. In this work, assisted with density functional theory (DFT) modelling, we study the electronic band structure of aluminum (Al)-doped TiO2 (ATO). The atomic-layer-deposited (ALD) ATO thin films are successfully prepared, and the elemental analysis, passivation effect, thermal stability, conductivity and optical properties of the ATO are systematically investigated. An ultra-high effective minority carrier lifetime (τeff) of 1.9 ms and a low contact resistivity (ρc) of 0.1 Ω·cm2 are simultaneously achieved on silicon wafers. Meanwhile, it is found that the ATO thin films possess better thermal stability than the TiO2 thin film. Finally, a large-area (118.7 × 100 mm2) p-type passivated emitter and rear contact (PERC) solar cells integrated with an ALD ATO layer on the illumination side was fabricated, and a champion efficiency of 21.4% was achieved with an optimal Al concentration in ATO, which is significantly higher than a PERC solar cell with intrinsic TiO2. This work shows ATO a very attractive alternative achieving high-efficiency crystalline silicon solar cells.

Nonthermal plasma synthesized silicon-silicon nitride core–shell nanocrystals with enhanced photoluminescence

Enhanced optical properties of silicon quantum dots (QDs) are pertinent for light-emitting applications including luminescent solar cell concentrators. Surface passivation plays a crucial role in improving photoluminescent quantum yield and effective carrier lifetimes of silicon nanocrystals and is often achieved by surface grafting of organic ligands. However, organically passivated silicon QDs often suffer from a deterioration of the optical properties when exposed to the environment. In this work, we explore the effect of an inorganic amorphous silicon nitride (SiN x ) shell on silicon QDs and their optical properties. Utilizing a dual plasma approach with dual injection ports, we synthesized Si/SiN x core–shell nanoparticles using SiH4, NH3, H2, and Ar. The core–shell nanocrystals were characterized using optical and structural methods, which revealed that higher nitridation plasma powers could lead to Si precipitation altering the composition of SiN x shell. While as-synthesized Si/SiN x core–shell nanocrystals did not exhibit photoluminescence, oxidized Si/SiN x core–shell nanocrystals show significantly higher quantum yield (35%) and longer carrier lifetime compared to their bare oxidized Si analogues even after an environmental exposure of six months.

The effect of MoO3 interlayer on electro-physical characteristics of the perovskite solar cells

This report shows that sequentially deposited CuPc and MoOx films are an effective hole-transport layer (HTL) for perovskite solar cells (PSCs). PSCs with only CuPc hole-transport layer have a low power conversion efficiency (PCE) of 3.51%, which mostly due to a poor fill factor (FF) of 29.4%. The incorporation of the MoOx interlayer between the CuPc layer and the anode (Ag) significantly boosted device FF and PCE up to 63.2% and 8.12%, respectively. The analysis of the impedance spectra of PSCs indicates that the MoOx interlayer reduces HTL resistance and increases the recombination resistance at the perovskite/HTL interface, which increases an effective charge carrier lifetime. Moreover, MoOx electric transport properties depends on the stoichiometry of the crystal structure, which can be varied by tuning vacuum level during the thermal sputtering of MoOx layers. PSCs based on the MoOx layer deposited at low vacuum (10−2 Pa) have reached PCE of 8.12% owing to the optimization of the interlayer energy levels and electric transport properties of MoOx films. In this work, we have developed the double hole-transport layer (HTL) for PSCs, which can prevent perovskite degradation on perovskite/HTL interface and hinder a severe charge recombination.

Study on Annealing Process of Aluminum Oxide Passivation Layer for PERC Solar Cells

In this study, Atomic Layer Deposition (ALD) equipment was used to deposit Al2O3 film on a p-type silicon wafer, trimethylaluminum (TMA) and H2O were used as precursor materials, and then the post-annealing process was conducted under atmospheric pressure. The Al2O3 films annealed at different temperatures between 200–500 °C were compared to ascertain the effect of passivation films and to confirm the changes in film structure and thickness before and after annealing through TEM images. Furthermore, the negative fixed charge and interface defect density were analyzed using the C-V measurement method. Photo-induced carrier generation was used to measure the effective minority carrier lifetime, the implied open-circuit voltage, and the effective surface recombination velocity of the film. The carrier lifetime was found to be the longest (2181.7 μs) for Al2O3/Si post-annealed at 400 °C. Finally, with the use of VHF (40.68 MHz) plasma-enhanced chemical vapor deposition (PECVD) equipment, a silicon nitride (SiNx) film was plated as an anti-reflection layer over the front side of the wafer and as a capping layer on the back to realize a passivated emitter and rear contact (PERC) solar cell with optimal efficiency up to 21.54%.

Lateral Charge Carrier Transport in Cu(In,Ga)Se2 Studied by Time‐Resolved Photoluminescence Mapping

Electronic transport in a semiconductor is key for the development of more efficient devices. In particular, the electronic transport parameters carrier lifetime and mobility are of paramount importance for the modeling, characterization, and development of new designs for solar cells and optoelectronic devices. Herein, time‐resolved photoluminescence mapping under low injection and wide‐field illumination conditions is used to measure the carrier lifetime and analyze the lateral charge carrier transport in Cu(In,Ga)Se2 absorbers grown at different temperatures, on different substrates, and subject to different postdeposition treatments (PDT) with light or heavy alkalis. To estimate the carrier mobility, numerical simulations of carrier diffusion transport to areas of increased recombination (defects) are used, similarly as observed experimentally. Mobilities are found in the range of 10–50 cm2 V−1 s−1, and effective minority carrier lifetime between 100 and 800 ns resulting in carrier diffusion lengths of 2–9 μm depending on the sample. Finally, the factors limiting carrier mobility and the implications of carrier diffusion on the measured carrier lifetimes are discussed.

Impact of chemically grown silicon oxide interlayers on the hydrogen distribution at hydrogenated amorphous silicon/crystalline silicon heterointerfaces

We studied the impact of oxidizing pre-treatments (OPT) and post deposition annealing (PDA) on the passivation performance and the hydrogen distribution near the interface between crystalline silicon (c-Si) and hydrogenated amorphous silicon (a-Si:H), the critical functional region in Si heterojunction solar cells. The OPT prior to deposition of the a-Si:H layer consists of immersing the c-Si substrates into hydrogen peroxide solutions, which forms a silicon oxide interlayer. Spectroscopic ellipsometry (SE) indicates that slightly thicker a-Si:H layers result from OPT. The refractive index and the extinction coefficient are increased by inserting the oxide interlayers, suggesting that less deficient and denser a-Si:H layers can be formed. Under optimum conditions, OPT leads to at least 2-fold improvement of the effective photo-generated carrier lifetime. PDA at 200 °C further improves the passivation performance of samples with an interlayer. Hydrogen profiling with nuclear reaction analysis clarifies that higher hydrogen concentrations are present around the heterointerfaces of samples with an interlayer and that these hydrogen concentrations are maintained after PDA. Our results suggest that the oxide interlayer can suppress hydrogen desorption in the initial growth stage of high-quality a-Si:H layers and during subsequent PDA, resulting in excellent passivation performance.

Coupled Investigation of Contact Potential and Microstructure Evolution of Ultra-Thin AlOx for Crystalline Si Passivation.

In this work, we report the same trends for the contact potential difference measured by Kelvin probe force microscopy and the effective carrier lifetime on crystalline silicon (c-Si) wafers passivated by AlOx layers of different thicknesses and submitted to annealing under various conditions. The changes in contact potential difference values and in the effective carrier lifetimes of the wafers are discussed in view of structural changes of the c-Si/SiO2/AlOx interface thanks to high resolution transmission electron microscopy. Indeed, we observed the presence of a crystalline silicon oxide interfacial layer in as-deposited (200 °C) AlOx, and a phase transformation from crystalline to amorphous silicon oxide when they were annealed in vacuum at 300 °C.

Phosphorus-doped polysilicon passivating contacts deposited by atmospheric pressure chemical vapor deposition

In this work, we present a high quality tunnel oxide passivating, electron-selective contact that is formed using an in-situ phosphorus-doped polycrystalline silicon (poly-Si) layer deposited using an in-line atmospheric pressure chemical vapor deposition (APCVD) process. In-line APCVD is a single-sided deposition process that does not require vacuum systems and is well suited for high volume manufacturing. To fabricate this tunnel oxide passivating contact (TOPCon), we deposit an amorphous silicon (a-Si) layer on silicon oxide (SiO) passivated n-type crystalline silicon (c-Si) followed by an annealing step at around 910 ∘C, which provides solid phase crystallization. The contact shows an excellent surface passivation quality with an effective minority carrier lifetime of ≈4.2 ms and an implied open circuit voltage (iV ) of ≈717 mV after annealing without any additional hydrogenation process. Saturation current density (J ) of ≈18 fA cm−2 is recorded for this contact. Contact resistivity () of ≈50 mΩ·cm−2 and junction resistivity of ≈0.24 Ω·cm−2 are realized with e-beam evaporated aluminium (Al) metal contact.

(Invited) Gallium Doped Silicon for High Efficiency Solar Cells

In the past year or so, gallium doped silicon wafers have become a mainstream substrate for solar cell production in China [1], and hence for the world. They offer intrinsically better carrier lifetime stability than boron doped substrates [2] without requiring post-cell production stabilisation processes while requiring only minimal changes to established cell lines. Gallium doped monocrystalline silicon is likely to account for the majority of passivated emitter and rear cell (PERC) production in the coming years.High purity gallium doped silicon has been the subject of much less study than some other silicon material types, and the limits of its performance are not yet well established. In terms of effective carrier lifetime – one of the most important properties for solar cells – the highest reported values are typically around 1 ms. We have conducted a study to evaluate the performance limit of modern Ga doped silicon materials with high quality surface passivation. We find effective lifetime to vary with resistivity and measure effective lifetimes > 9 ms in 11.2 Ωcm material, which is much higher than reported previously. Furthermore, the injection dependence is less strong than in the boron case which may result in a higher fill factor and favourable cell performance in operation.One of Ga doped silicon’s perceived advantages is its stability under illumination relative to B doped silicon which suffers heavily from boron-oxygen light induced degradation if not mitigated. We have monitored the stability of commercial gallium doped PERC cells under illumination (> 3000 h in some cases) using a photoluminescence imaging proxy method. We have shown however that dark annealed Ga doped PERC cells can degrade when exposed to light, albeit on a much smaller scale than B doped PERC, and this degradation occurs due to a reduction in bulk lifetime [3]. We will now present our latest results which show inconsistencies in degradation behaviour between solar cell batches. Surprisingly, cells from one ingot exhibit degradation, then recovery behaviour when annealed at 300 °C, but near stability when not annealed, but, for another ingot, the opposite is observed. We have also investigated the effect of stabilisation processes of the kind typically used to mitigate boron-oxygen degradation. We find these processes make essentially no difference to the degradation behaviour in Ga doped PERC cells. Our investigations using secondary ion mass spectrometry (SIMS) find that commercial Ga doped PERC cells contain detectable levels of boron, and this could play a role in the degradation processes observed.In summary, our work generally confirms the positive effects of a transition from B to Ga doping for solar cells. Any degradation in cell performance under illumination is fairly small, but understanding the reasons for this is one of the most important questions in high purity silicon research at present. We will highlight urgent research in this area necessary to mitigate instability issues which may arise in newly manufactured modules featuring Ga doped silicon solar cells.

Effect of the native oxide on the surface passivation of Si by Al2O3

The effect of the native silicon oxide layer on the passivation properties of Al2O3 on p-type Si surfaces has been investigated. This was done by comparing effective carrier lifetime, surface saturation current density, fixed charge, and density of interface states of samples, where the native oxide was not removed prior to Al2O3 passivation, with samples subjected to a 3 min HF-dip. The sample with the native oxide exhibits excellent surface passivation post-annealing, with a surface saturation current density of 13 fA/cm2 and significantly longer effective lifetime compared to the sample, where the native oxide was removed. Capacitance–voltage measurements of a sample with the native oxide revealed a remarkably low density of interface states (1010 eV−1 cm−2), almost three times lower than a sample where the native oxide was removed prior to Al2O3 deposition. The results indicate that a thin layer of native oxide improves the Al2O3 surface passivation of silicon.

CdTe X/γ-ray Detectors with Different Contact Materials.

Different contact materials and optimization of techniques of their depositions expand the possibilities to obtain high performance room temperature CdTe-based X/γ-ray detectors. The heterostructures with ohmic (MoOx) and Schottky (MoOx, TiOx, TiN, and In) contacts, created by DC reactive magnetron sputtering and vacuum thermal evaporation, as well as In/CdTe/Au diodes with a p-n junction, formed by laser-induced doping, have been developed and investigated. Depending on the surface pre-treatment of semi-insulating p-CdTe crystals, the deposition of a MoOx film formed either ohmic or Schottky contacts. Based on the calculations and I-V characteristics of the Mo-MoOx/p-CdTe/MoOx-Mo, In/p-CdTe/MoOx-Mo, Ti-TiOx/p-CdTe/MoOx-Mo, and Ti-TiN/p-CdTe/MoOx-Mo Schottky-diode detectors, the current transport processes were described in the models of the carrier generation–recombination within the space-charge region (SCR) at low bias, and space-charge limited current incorporating the Poole–Frenkel effect at higher voltages, respectively. The energies of generation–recombination centers, density of trapping centers, and effective carrier lifetimes were determined. Nanosecond laser irradiation of the In electrode, pre-deposited on the p-CdTe crystals, resulted in extending the voltage range, corresponding to the carrier generation–recombination in the SCR in the I-V characteristics of the In/CdTe/Au diodes. Such In/CdTe/Au p-n junction diode detectors demonstrated high energy resolutions (7%@59.5 keV, 4%@122 keV, and 1.6%@662 keV).