Room-temperature Semiconductor Research Articles

Multiple non-covalent interactions synergistically construct room-temperature photoferroelectric semiconductor (Cl-PA)2PbCl4

Two-dimensional single-phase magnetoelectric multiferroic semiconductors are attractive for the multifunctional spintronic nanodevices due to their cross coupling between coexisting magnetic and ferroelectric orders. However, experimentally synthesized two-dimensional magnetoelectric multiferroic materials are very rare to date because of the mutual exclusion between ferroelectricity and magnetism. Here, we predict a two-dimensional room-temperature ferromagnetic multiferroic Ti2F3 semiconductor through the first-principles calculations and Monte Carlo simulations. The Ti2F3 monolayer manifests an easy magnetization plane, and the magnitude of the out-of-plane polarization is 0.037 C/m2. Interestingly, the magnetic ground states of the Ti2F3 monolayer can be tuned by the electric field. Moreover, we explore the electric field tunable magneto-optical effects in the Ti2F3 monolayer. Our work provides more magnetoelectric multiferroic candidate materials and suggests an effective strategy to realize and probe the magnetic phase transition.

Two-dimensional hybrid nanosheets towards room-temperature organic ferrimagnetic semiconductor

Abstract Magnetic nodal-line semiconductors, characterized by colossal magnetoresistance due to the lifting of spin orientation-dependent topological band degeneracy, hold great potential for advanced spintronic applications. However, a key challenge for the practical use of such topological magnets is their low magnetic transition temperature (T C). Through first-principles calculations, we identify the self-intercalated van der Waals ferrimagnet Tc3Si2Te6 as a high-T C (~268 K) magnetic nodal-line semiconductor. Furthermore, we find that magnetic nodal-line semiconductors can exist in dually doped Tc3(Si1-α Y α )2(Te1-β Z β )6 (Y = Ge and Sn; Z = S and Se) over a broad range of α and β. Particularly, Tc3(Si0.05Ge0.95)2(Te0.70Se0.30)6 is shown to be a near room-temperature magnetic nodal-line semiconductor with a sizable band gap. Our findings suggest Tc-based self-intercalated van der Waals ferrimagnets are promising magnetic nodal-line semiconductors for practical applications in spintronic devices.

Harvesting prominent room-temperature layered organic ferrimagnetic semiconductors: the importance of interfacial coordination

The discovery of two-dimensional (2D) ferromagnetic semiconductors holds significant promise for advancing Moore's law and spintronics in-memory computing, sparking tremendous interest. However, the Curie temperature of explored 2D ferromagnetic semiconductors is much lower than room temperature. Although plenty of 2D room-temperature ferromagnetic semiconductors have been theoretically predicted, there have been formidable challenges in preparing such metastable materials with ordered structures and high stability. Here, utilizing a novel template-assisted chemical vapor deposition strategy, we synthesized layered MnS2 microstructures within a ReS2 template. The high-resolution atomic structure representation revealed that monolayer MnS2 microstructures well crystallize into a distorted T-phase. Room-temperature ferromagnetism was confirmed through vibrating sample magnetometer measurements, microzone magnetism imaging techniques, and transport characterization. Theoretical calculations indicated that the room-temperature ferromagnetism originates from the Mn-Mn short-range interaction. Our observation not only offered the experimental confirmation of the intrinsic room-temperature ferromagnetism in layered MnS2, but also provided an innovative strategy for the growth of 2D metastable functional materials.

Abstract Interfacing light from solid-state single-photon sources with scalable and robust room-temperature quantum memories has been a long-standing challenge in photonic quantum information technologies due to inherent noise processes and time-scale mismatches between the operating conditions of solid-state and atomic systems. Here, we demonstrate storage of single photons from a semiconductor quantum dot (QD) device in a room-temperature atomic vapor memory and their on-demand retrieval. A deterministically fabricated InGaAs QD light source emits single photons at the wavelength of the cesium D1 line at 895 nm which exhibit an inhomogeneously broadened linewidth of 5.1(7) GHz and are subsequently stored in a low-noise ladder-type cesium vapor memory. We show control over the interaction between the single photons and the atomic vapor, allowing for variable retrieval times of up to 19.8(3) ns. A maximum internal efficiency of η int = 0.6 ( 1 ) % is achieved. Our results expand the application space of both room-temperature vapor memories and semiconductor QDs in future quantum network architectures.

Abstract Realizing ferromagnetic semiconductors with high Curie temperature T C is still a challenge in spintronics. Recent experiments have reported two-dimensional (2D) room temperature ferromagnetic metals, such as monolayer Cr3Te6. In this paper, by the density functional theory (DFT) calculations, we proposed a way to obtain 2D high T C ferromagnetic semiconductors through element replacement in these ferromagnetic metals. We predict that monolayer (Cr4/6, Mo2/6)3Te6, created via element replacement in monolayer Cr3Te6, is a room-temperature ferromagnetic semiconductor exhibiting a band gap of 0.34 eV and a T C of 384 K. Our analysis reveals that the metal-to-semiconductor transition stems from the synergistic interplay of Mo-induced lattice distortion, which resolves band overlap, and the electronic contributions of Mo dopants, which further drive the formation of a distinct band gap. The origin of the high T C is traced to strong superexchange coupling between magnetic ions, analyzed via the superexchange model with DFT and Wannier function calculations. Considering the fast developments in fabrication and manipulation of 2D materials, our theoretical results propose a way to explore the high temperature ferromagnetic semiconductors from experimentally obtained 2D high temperature ferromagnetic metals through element replacement.

Room-temperature bipolar ferrovalley semiconductors and anomalous valley Hall effect in Janus CeClI and CeBrI

This study focuses on the developing a simple analog Multi-Channel Analyzer (MCA) integrated into a Programmable System-on-Chip (PSoC). The primary objective is to facilitate the incorporation of MCA functionality into radiation measurement instrumentations and the popularization of use in educational settings. To achieve this goal, practical design requirements were defined for the spectrometer using scintillation detectors and room-temperature semiconductor detectors. Techniques for improving the differential non-linearity (DNL) of the built-in Analog-to-Digital Converter (ADC), minimizing dead time, and optimizing CPU resources for processing 100 kHz periodic pulse were developed and validated. All MCA functions, including the newly developed techniques, were successfully implemented on one chip, the PSoC5LP. The resultant MCA, named TinyMCA, underwent testing of gamma-ray spectrum measurement, demonstrating proper functionality and achieving the performance goals. Additionally, the appendix presents an example where shaping amplifier functions, such as pulse shaping, voltage amplification, and baseline restoration, could be incorporated alongside the TinyMCA features. This integration allows for easy pulse height spectrum measurements using only a one-chip, TinyMCA when there is a detector equipped with a preamplifier.

Narrow-gap Fe-doped III–V ferromagnetic semiconductors (FMSs), such as (In,Fe)Sb, (Ga,Fe)Sb, and (In,Fe)Sb, are promising candidates for active semiconductor spintronic devices thanks to their high Curie temperature (TC). In this work, we show that by growing (Ga,Fe)Sb thin films by the step-flow mode on vicinal GaAs (100) substrates with a high off-angle of 10°, we can achieve high-quality (Ga0.76,Fe0.24)Sb FMS with TC as high as 470–530 K, which are the highest TC reported so far for FMSs. The magnetic moment of Fe atoms in our sample reaches 4.5 μB/atom, which is close to the ideal magnetic moment of substitutional Fe3+ atoms (5 μB/atom) in a zinc blende crystal structure, and is twice that of α-Fe metal. Our work establishes a growth technique of very high TC FMSs for room-temperature semiconductor spintronic devices.

Room-temperature dilute magnetic semiconductor behavior in nonmagnetic Ti4+-doped CeO2 nanoflowers for efficient spintronics and photocatalytic applications

This review explores the applications of room temperature semiconductor detectors, with a focus on Cd(Zn)Te based detection systems, in non-destructive testing and evaluation (NDT&E). Cd(Zn)Te detectors, which operate efficiently at ambient temperatures, eliminate the need for cryogenic cooling systems and offer high energy and spatial resolution, making them ideal for a wide range of NDT&E applications. Key performance parameters such as energy resolution, spatial resolution, time resolution, detector efficiency, and form factor are discussed. The paper highlights the utilization of Cd(Zn)Te detectors in various imaging and spectroscopic applications, including nuclear threat detection and non-proliferation, archaeological NDT, and Unmanned Aerial Vehicle radiological surveying. Cd(Zn)Te detectors hold significant promise in NDT&E due to their high-resolution imaging, superior spectroscopic capabilities, versatility, and portability.

Wearable gas sensors offer remarkable advantages in terms of portability and real-time monitoring, rendering them highly promising for various applications such as environmental detection, health monitoring, and early disease diagnosis. However, the most widely used oxide semiconductor gas sensors encounter substantial challenges in achieving mechanical flexibility and room-temperature gas detection due to their inherent rigidity, brittleness, and reliance on high operating temperatures. Herein, an all-inorganic wearable oxide semiconductor gas sensor is fabricated by depositing the anatase/rutile TiO2 (TiO2-A/R) homojunction on a flexible yttria-stabilized zirconia (YSZ) nanofiber substrate using atomic layer deposition technology. The combination of the YSZ nanofiber and the ultrathin TiO2 sensing layer (∼13 nm) endows the wearable sensor with tiny linear strains (0.55%) when subjected to a radius of curvature of 25 μm. As a result, the wearable inorganic YSZ/TiO2-A/R sensor can be folded multiple times without fracturing and maintain a stable electrical connectivity during cyclic bending. Furthermore, the utilization of photoactive TiO2 homojunctions allows the sensor to be activated by UV light and operated at room temperature. The efficient separation efficiency of photogenerated carriers, which stems from the interfacial electric field of TiO2 homojunctions, significantly enhances the sensor's response, leading to a low detection limit of 0.15 ppm for acetone. In addition, the wearable sensor was anchored on a mask and successfully utilized for the detection of a simulated breathing gas of diabetics; the real-time and stable response signals demonstrate its potential for noninvasive diabetes diagnosis. This study provides a valuable reference for the advancement of wearable room-temperature inorganic semiconductor gas sensors, offering valuable insights into their potential applications in disease diagnosis.

Developing purely organic room-temperature magnetic semiconductors has been a long-sought goal in the material community toward the simultaneous control of spin and charge. Organic cocrystals, known for their structural versatility and multifunctionality, are ideal candidates for these magnetoelectric coupling applications. However, organic room-temperature magnetic semiconductor cocrystals have rarely been reported, and their mechanisms remain poorly understood due to the complexity of cocrystal structures. Here, doping organic cocrystals with radicals offers a promising strategy for boosting their magnetism and conductivity while maintaining their cocrystal structures. The fluoranthene-7,7,8,8-tetracyanoquinodimethane radical (FA-HTCNQ•) is constructed through a simple, rapid, and eco-friendly solution-processing approach. The conductive FA-HTCNQ• exhibits excellent room-temperature ferromagnetism with the coercive fields of 96 Oe and the Curie temperature near 400 K, superior to its structural-identical undoped counterpart. Meanwhile, the room-temperature magnetoelectric coupling is demonstrated in the conductive FA-HTCNQ•. The stronger ferromagnetism and conductivity in organic cocrystals are attributed to the enhanced charge-transfer (CT) interactions induced by radicals, rather than the spin exchange interactions between these radicals alone. The research manifests the origin of ferromagnetism in organic cocrystals and provides a simple strategy to fabricate pure organic room-temperature magnetic semiconductor materials for future integrated magnetoelectric devices.

CdZnTe (CZT) has garnered substantial attention due to its outstanding performance in room-temperature semiconductor radiation detectors, where carrier transport properties are critical for assessing the detector performance. However, due to the complexities of crystal growth, CZT is prone to defects that affect carrier lifetime and mobility. To investigate how defects affect nonequilibrium carrier transport, nonadiabatic molecular dynamics (NAMD) is employed to examine six types of intrinsic defects and their impact on electron-hole (e-h) recombination. The findings reveal that Te substitution at the Cd site (TeCd) and Te interstitial (Tei) defects expedite recombination by introducing intermediate energy levels. The coupling of new energy levels in Te vacancy (VTe) with the conduction band minimum (CBM) slows down electron release and results in an extended recombination time. Cd substitution at the Te site (CdTe) and Cd interstitial (Cdi) defects enhance nonadiabatic coupling (NAC) to accelerate the recombination. In contrast, Cd vacancy (VCd) diminishes NAC through weakening carrier coupling with high-frequency phonons and leads to a deceleration of the recombination rate. Overall, the intrinsic defects may change electron structures to vary NAC, which is critical for the recombination rate. It is believed that this research may benefit the understanding of defects on the carriers' lifetime in CZT and provide hints for further optimizing the performance of CZT material in nuclear radiation detection.

A spintronic device based on a skyrmion transistor, designed to perform specific functions by encoding “0” and “1” using VXY Janus structures.

The recently discovered metal-like room-temperature plasticity in inorganic semiconductors reshapes our knowledge of the physical properties of materials, giving birth to a series of new-concept functional materials. However, current room-temperature plastic inorganic semiconductors are still very rare, and their performance is inferior to that of classic brittle semiconductors. Taking classic bismuth telluride (Bi2Te3)-based thermoelectric semiconductors as an example, we show that antisite defects can lead to high-density, diverse microstructures that substantially affect mechanical properties and thus successfully transform these bulk semiconductors from brittle to plastic, leading to a high figure of merit of up to 1.05 at 300 kelvin compared with other plastic semiconductors, similar to the best brittle semiconductors. We provide an effective strategy to plastify brittle semiconductors to display good plasticity and excellent functionality simultaneously.

The material family halide perovskites has been critical in recent room-temperature radiation detection semiconductor research. Cesium lead bromide (CsPbBr3) is a halide perovskite that exhibits characteristics of a semiconductor that would be suitable for applications in various fields. In this paper, we report on the correlations between material purification and crystal material properties. Crystal boules of CsPbX3 (where X = Cl, Br, I, or mixed) were grown with the Bridgman growth method. We describe in great detail the fabrication techniques used to prepare sample surfaces for contact deposition and sample testing. Current-voltage measurements, UV-Vis and photocurrent spectroscopy, as well as photoluminescence measurements, were carried out for material characterization. Bulk resistivity values of up to 3.0 × 109 Ω∙cm and surface resistivity values of 1.3 × 1011 Ω/□ indicate that the material can be used for low-noise semiconductor detector applications. Preliminary radiation detectors were fabricated, and using photocurrent measurements we have estimated a value of the mobility-lifetime product for holes (μτ)h of 2.8 × 10-5 cm2/V. The results from the sample testing can shed light on ways to improve the crystal properties for future work, not only for CsPbX3 but also other halide perovskites.

Optical and electric properties of tin oxide (SnO2) with reduced graphene oxide nanocomposite thin films