Baoshun Zhang's research while affiliated with SiNANO and other places

High-quality unintentionally doped (UID) (001) β-Ga2O3 homoepitaxial films were grown on native substrates through metalorganic chemical vapor deposition. The surface parallel grooves were repaired under low temperature and pressure condition, reaching the surface roughness of 2.22 nm and the high electron mobility of 74.6 cm2/Vs. Enhancement-mode metal–oxide–semiconductor field-effect transistors were fabricated on the UID β-Ga2O3 film, showing a positive turn-on threshold gate voltage of 4.2 V and a breakdown voltage of 673V. These results can serve a reference for (001) oriented lateral Ga2O3 power transistors and may contribute to the development of Ga2O3 power devices.

GaN metal–insulator–semiconductor high electron mobility transistors (MIS-HEMTs) with scandium aluminum nitride Sc0.2Al0.8N/SiNX composite gate dielectric were demonstrated with improved device performance in terms of current density, on-resistance, breakdown voltage, gate leakage, and current collapse. GaN MIS-HEMTs with single-layer Sc0.2Al0.8N or SiNX were also fabricated as reference. Notably, the current collapse was reduced from ∼38.8% in GaN MIS-HEMTs with single-layer SiNX dielectric to ∼4.9% in the device with composite gate dielectric. The insertion of the thin SiNX layer can mitigate the surface damage due to the ScAlN sputtering process and significantly reduce the interface state density. Furthermore, the high valence band offset of Sc0.2Al0.8N/SiNX of 0.78 eV also plays a key role in the suppression of hole injection and gate leakage current. This work shows the effectiveness of the Sc0.2Al0.8N/SiNX composite gate dielectric and can serve as an important reference for future developments of high-performance reliable GaN HEMTs for power and RF electronics.

The use of two-dimensional materials and van der Waals heterostructures holds great potential for improving the performance of memristors Here, we present SnS2/MoTe2 heterostructure synaptic transistors. Benefiting from the ultra-low dark current of the heterojunction, the power consumption of the synapse is only 19 pJ per switching under 0.1 V bias, comparable to that of biological synapses. The synaptic device based on the SnS2/MoTe2 demonstrates various synaptic functionalities, including short-term plasticity, long-term plasticity, and paired-pulse facilitation. In particular, the synaptic weight of the excitatory postsynaptic current can reach 109.8%. In addition, the controllability of the long-term potentiation and long-term depression are discussed. The dynamic range (G max/G min) and the symmetricity values of the synaptic devices are approximately 16.22 and 6.37, and the non-linearity is 1.79. Our study provides the possibility for the application of 2D material synaptic devices in the field of low-power information storage.

In power conversion systems, the power devices often need to block high voltage levels during the OFF-state. The impact of such voltage stress can cause instability for the device. This article presents the investigation of the pulsed I – V (PIV) OFF-state drain stress test for the etch-free hydrogen plasma-treated p-GaN gate HEMT (H-treated devices). To quantitatively demonstrate the effect of the hydrogen plasma treatment process, the device with conventional p-GaN etching at the access region (etched devices) is monolithically fabricated. Remarkably, the hydrogen treatment could eliminate surface damage from the conventional etching process and provide passivation at the access region. The direct comparison of devices’ threshold voltage ( V $_{\text{TH}}$ ) shift and dynamic ON-resistance ( R $_{\text{on}}$ ) is obtained. Under a 200-V OFF-state drain stress, the H-treated device has a low V $_{\text{TH}}$ shift of 0.18 V, and the dynamic R $_{\text{on}}$ could also be efficiently suppressed by 24%. Meanwhile, the H-treated device has only a marginal 5% current reduction compared with 48% for the etched device at 200-V stress. An exploration of the origin of the superior device performances is carried out with the TCAD simulation, activation energy derivation, and capacitance measurement. For the H-treated device, the surface state improvement at the region and the reduction of the peak electric field at the gate edge become major reasons for the improved performance.

Quasi‐vertical GaN trench‐gate MOSFETs with different etch RF power and the impact of the order of annealing process in TMAH wet treatment have been fabricated and studied. The high‐power device has a threshold voltage of 5.3 V and a maximum saturation current density of 552 A/cm ² , whereas the low‐power device has a threshold voltage of 4.5 V and a maximum saturation current density of 650 A/cm ² . However, the low‐power device has more severe off‐state leakage due to more fixed charges and defects on the device surface. Furthermore, the annealing process serves as an additional step before wet treatment. SEM image indicates that annealing at high temperatures prior to etching can eliminate surface oxide and redistribute surface imperfections, resulting in a smoother sidewall morphology. The relationship between temperature and mobility confirms the impact of the crystal surface feature on device performance. This article is protected by copyright. All rights reserved.

This study presents a comparative analysis of AlGalnAs buried heterostructure laser diodes by using dual-channel ridge-waveguides. Different shaped channels, including bowl shaped groove and vertical groove, are explored. Using a vertical groove structure, we achieved an output power of 90 mW at 25 °C with a threshold current of only 4 mA. This represents a 3.6-fold increase in output power compared to the BH-DFB structure. At a high temperature of 85 °C, the laser maintains a side-mode suppression ratio of over 45 dB at the maximum power point. The laser’s relative intensity noise in the 0–40 GHz frequency range is less than −162.8 dB/Hz when operated at 300 mA with the chip butterfly packaged. These findings underscore the robustness, reliability, and high-performance capabilities of the developed DFB laser, highlighting its potential for various practical applications.

Oxygen vacancies (Vo) can significantly degrade the electrical properties of indium oxide (In2O3) thin films, thus limiting their application in the field of ultraviolet detection. In this work, the Vo is effectively suppressed by adjusting the Trimethylindium (TMIn) flow rate (fTMIn). In addition, with the reduction of the fTMIn, the background carrier concentration and the roughness of the film decrease gradually. And a smooth In2O3 thin film with roughness of 0.44 nm is obtained when the fTMIn is 5 sccm. The MSM photodetectors (PDs) are constructed based on In2O3 thin films with different fTMIn to investigate the opto-electric characteristics of the films. The dark current of the PDs is significantly reduced by five orders from 100 mA to 0.28 μA with the reduction of the fTMIn from 50 sccm to 5 sccm. In addition, the photo response capacity of PDs is dramatically enhanced. The photo-to-dark current ratio (PDCR) increases from 0 to 2589. Finally, the PD with the fTMIn of 5 sccm possesses a record-high responsivity of 2.53 × 103 AW−1, a high detectivity of 5.43 × 107 Jones and a high EQE of 9383 × 100%. Our work provides an important reference for the fabrication of high-sensitivity UV PDs.

The growing market and massive use of Internet of Things nodes is placing unprecedented demands of energy efficient hardware for edge computing and microwave devices. In particular, magnetic tunnel junctions (MTJs), as main building blocks of spintronic microwave technology, can offer a path for the development of compact and high-performance microwave detectors. On the other hand, the fascinating field of skyrmionics is bridging together concepts from topology and spintronics. Here, we show the proof of concept of a topological spin-torque diode realized with an MTJ on top of a skyrmionic material at room temperature and for a wide region of applied fields, including the zero-field case. Our spin torque diode electrical measurements show the electrical excitation of a skyrmion resonant mode with frequencies near 4 GHz and a selectivity one order of magnitude smaller than the uniform modes excited in the same device. Micromagnetic simulations identify these dynamics with the excitation of the breathing mode and point out the role of thickness dependent magnetic parameters (magnetic anisotropy field and Dzyaloshinkii Moriya interaction) in both stabilizing and exciting the magnetic skyrmions. This work marks a milestone for the development of topological spin-torque diodes.

Quantitative assessments of the level and lifetime of alkali metal in the atomic vapor cells are essential for improving the stability of atomic magnetometers. In this paper, a fast and non-destructive approach is proposed to directly characterize the level of ⁸⁷ Rb in a hermetic MEMS vapor cell. The MEMS-compatible ⁸⁷ Rb evaporation technique is developed to dispense ⁸⁷ Rb in the vapor cells with high efficiency. The morphology of the metallic ⁸⁷ Rb in the MEMS vapor cell is visualized by the non-destructive X-ray technique, and the measured contact angle is 43° ± 2°. Combined with the image recognition, the quantitative characterization of the ⁸⁷ Rb is achieved, and the consumption rates of ⁸⁷ Rb in MEMS cells are experimentally investigated. The presented approach is beneficial for the fabrication and performance enhancement of vapor cells for atomic magnetometers.

This work conducted a comparative study on DFB lasers based on AlGaInAs/InP heterostructures, and comparatively studied the effects of different trench shapes and different cavity lengths on the laser output characteristics. Based on the vertical trench structure, we obtained a laser output of 90mW at 25°C, Compared with the trenchless laser, the output power was increased to 3.6 times the original, and the threshold current was only 4mA. It allows 8.5nm wavelength tunability within the temperature range of 5-85℃, and still has an edge mode suppression ratio of >45dB at 85℃. After the chip is packaged in a butterfly shape, the relative intensity noise in the 0-40 GHz frequency range is lower than -162.8dB/Hz at the working current of 300mA.