AlGaN-based deep-ultraviolet(DUV)laser diodes(LDs)face performance challenges due to elec-tron leakage and poor hole injection which is often worsened by polarization effects from conventional elec-tron blocking layer...AlGaN-based deep-ultraviolet(DUV)laser diodes(LDs)face performance challenges due to elec-tron leakage and poor hole injection which is often worsened by polarization effects from conventional elec-tron blocking layers(EBLs).To overcome these limitations,we propose an EBL-free DUV LD design incor-porating a 1-nm undoped Al_(0.8)Ga_(0.2)N thin strip layer after the last quantum barrier.Using PICS3D simula-tions,we evaluate the optical and electrical characteristics.Results show a significant increase in effective electron barrier height(from 158.2 meV to 420.7 meV)and a reduction in hole barrier height(from 149.2 meV to 62.8 meV),which enhance hole injection and reduce electron leakage.The optimized structure(LD3)achieves a 14%increase in output power,improved slope efficiency(1.85 W/A),and lower threshold current.This design also reduces the quantum confined Stark effect and forms dual hole accumulation regions,im-proving recombination efficiency.展开更多
High-temperature-annealed Al N(HTA-Al N) templates provide ideal substrates for high-quality Al Ga N epitaxy. However, the significant compressive stress accumulated within the Al Ga N layer makes it challenging to ac...High-temperature-annealed Al N(HTA-Al N) templates provide ideal substrates for high-quality Al Ga N epitaxy. However, the significant compressive stress accumulated within the Al Ga N layer makes it challenging to achieve a smooth surface free of hexagonal hillocks on these templates. To address this issue, we investigate the mechanism of compressive stress accumulation during the growth of Al Ga N-based epilayers on HTA-Al N templates using in-situ curvature analysis in this study. To verify the mechanism, a low-Al-content Al Ga N interlayer is introduced between the Al N epilayer and the subsequent Al Ga N epilayer. The larger a-plane lattice constant of this interlayer relative to the Al Ga N epilayer slows the accumulation rate of compressive stress. The hexagonal hillock can be effectively suppressed and the surface of Al Ga N epilayer can be significantly regulated by adopting various low-Al-content Al Ga N interlayers. This work provides a comprehension on the stress accumulation mechanism in Al Ga N epilayers and a feasible method to obtain hillock-free surface of Al Ga N epilayers on HTA-Al N templates,which will be beneficial for fabricating Al Ga N based devices.展开更多
Solar-blind ultraviolet photodetectors(UV PDs),capable of detecting UV radiation without interference from sun-light,have attracted significant interest.Herein,we propose a 0D/1D heterostructure for UV PDs,which was f...Solar-blind ultraviolet photodetectors(UV PDs),capable of detecting UV radiation without interference from sun-light,have attracted significant interest.Herein,we propose a 0D/1D heterostructure for UV PDs,which was fabricated by spin-coating MoS_(2)quantum dots onto p-AlGaN nanowires.The device achieves a high responsivity of 175.5 mA/W and a fast response speed of 83 ms at 250 nm illumination under self-powered mode,which improved nearly 1235%and 521%after MoS_(2)decoration,respectively.These improvements can be attributed to the type-Ⅱheterostructure formed between p-AlGaN and MoS_(2),which facilitates enhanced charge separation and carrier transport.Later,we demonstrate the implementation of this device in optical communication,achieving high-accuracy transmission of"GaN"ASCII code signals.Such a 0D/1D het-erostructure provides an effective strategy for high-performance solar-blind UV PD.展开更多
文摘AlGaN-based deep-ultraviolet(DUV)laser diodes(LDs)face performance challenges due to elec-tron leakage and poor hole injection which is often worsened by polarization effects from conventional elec-tron blocking layers(EBLs).To overcome these limitations,we propose an EBL-free DUV LD design incor-porating a 1-nm undoped Al_(0.8)Ga_(0.2)N thin strip layer after the last quantum barrier.Using PICS3D simula-tions,we evaluate the optical and electrical characteristics.Results show a significant increase in effective electron barrier height(from 158.2 meV to 420.7 meV)and a reduction in hole barrier height(from 149.2 meV to 62.8 meV),which enhance hole injection and reduce electron leakage.The optimized structure(LD3)achieves a 14%increase in output power,improved slope efficiency(1.85 W/A),and lower threshold current.This design also reduces the quantum confined Stark effect and forms dual hole accumulation regions,im-proving recombination efficiency.
基金supported by the National Key R&D Program of China (Grant No. 2022YFB3605000)the National Natural Science Foundation of China (Nos. 62004127, 61725403, 62121005, 61922078, 61827813, and 62004196)+1 种基金the Youth Innovation Promotion Association of Chinese Academy of Sciencesthe Youth Talent Promotion Project of the Chinese Institute of Electronics (No. 2020QNRC001)。
文摘High-temperature-annealed Al N(HTA-Al N) templates provide ideal substrates for high-quality Al Ga N epitaxy. However, the significant compressive stress accumulated within the Al Ga N layer makes it challenging to achieve a smooth surface free of hexagonal hillocks on these templates. To address this issue, we investigate the mechanism of compressive stress accumulation during the growth of Al Ga N-based epilayers on HTA-Al N templates using in-situ curvature analysis in this study. To verify the mechanism, a low-Al-content Al Ga N interlayer is introduced between the Al N epilayer and the subsequent Al Ga N epilayer. The larger a-plane lattice constant of this interlayer relative to the Al Ga N epilayer slows the accumulation rate of compressive stress. The hexagonal hillock can be effectively suppressed and the surface of Al Ga N epilayer can be significantly regulated by adopting various low-Al-content Al Ga N interlayers. This work provides a comprehension on the stress accumulation mechanism in Al Ga N epilayers and a feasible method to obtain hillock-free surface of Al Ga N epilayers on HTA-Al N templates,which will be beneficial for fabricating Al Ga N based devices.
基金supported in part by the National Natural Science Foundation of China(Grant Nos.52272168 and 62322410)the Anhui Provincial Natural Science Foundation(Grant No.2308085J08)USTC Bihe Youth Program for Interdisciplinary Innovation(Grant No.BH-202514).
文摘Solar-blind ultraviolet photodetectors(UV PDs),capable of detecting UV radiation without interference from sun-light,have attracted significant interest.Herein,we propose a 0D/1D heterostructure for UV PDs,which was fabricated by spin-coating MoS_(2)quantum dots onto p-AlGaN nanowires.The device achieves a high responsivity of 175.5 mA/W and a fast response speed of 83 ms at 250 nm illumination under self-powered mode,which improved nearly 1235%and 521%after MoS_(2)decoration,respectively.These improvements can be attributed to the type-Ⅱheterostructure formed between p-AlGaN and MoS_(2),which facilitates enhanced charge separation and carrier transport.Later,we demonstrate the implementation of this device in optical communication,achieving high-accuracy transmission of"GaN"ASCII code signals.Such a 0D/1D het-erostructure provides an effective strategy for high-performance solar-blind UV PD.
