现代应用物理2026，Vol.17Issue(4)：92-99,8.DOI:10.12061/j.issn.2095-6223.202605028
Fe-GaN共面电极光电导开关的光吸收特性研究
Optical Absorption Characteristics of Coplanar-Electrode Fe-GaN Photoconductive Semiconductor Switches
摘要
Abstract
Wide-bandgap photoconductive semiconductor switches(PCSS)have attracted considerable attention in pulsed-power and high-power microwave systems because of their high-voltage withstand capability,fast optical response,and inherent optical-electrical isolation.For gallium nitride(GaN)-based PCSS,the optical absorption behavior of the triggering laser is a key factor that determines the generation depth,spatial distribution,and effective transport of photogenerated carriers.In this paper,a coplanar-electrode Fe-GaN PCSS is triggered by front-side illumination using 355 nm and 532 nm laser pulses,and the transient output characteristics are investigated both experimentally and numerically.The 355 nm laser corresponds to above-bandgap excitation and mainly induces intrinsic band-to-band absorption,whereas the 532 nm laser corresponds to sub-bandgap excitation and is associated with Fe-related or defect-assisted absorption.The experimental results show that,within the bias voltage range of 0.5-3.5 kV,the output peak voltages for both excitation wavelengths increase approximately linearly with increasing bias voltage,indicating that the device operates mainly in a linear or weakly nonlinear photoconductive regime.At a bias voltage of 3 kV,the output peak voltages under 355 nm and 532 nm excitation are 664 V and 302 V,respectively,giving a peak-voltage ratio of about 2.2.The full-width-at-half-maximum(FWHM)values of the output pulses under the two excitation wavelengths are both approximately 0.29 ns.Numerical simulation indicates that 355 nm excitation produces a high-density photogeneration region near the incident surface because of strong intrinsic absorption,whereas 532 nm excitation exhibits much weaker absorption but deeper penetration into the bulk Fe-GaN region.Although the local initial photogeneration rate under 355 nm excitation is about three orders of magnitude higher than that under 532 nm excitation,the measured output peak voltage increases only by a factor of 2.2.This discrepancy indicates that the transient output of the Fe-GaN PCSS is not governed solely by the initial photogeneration rate.Instead,it is jointly determined by the number of absorbed photons,carrier spatial distribution,Fe-related deep-level trapping and recombination,carrier relaxation,space-charge screening,lateral electric-field transport,and external circuit coupling.These results clarify the distinct absorption mechanisms and effective carrier transport processes under intrinsic and defect-assisted sub-bandgap excitation,providing a physical basis for understanding wavelength-dependent transient responses in coplanar Fe-GaN PCSS.关键词
氮化镓/光电导开关/吸收机制/亚带隙吸收/能级跃迁Key words
gallium nitride/photoconductive semiconductor switch/absorption mechanism/sub-bandgap absorption/energy-level transition分类
信息技术与安全科学引用本文复制引用
屈坤,徐鸣,吕瑞东,张艺雯,宋昊..Fe-GaN共面电极光电导开关的光吸收特性研究[J].现代应用物理,2026,17(4):92-99,8.基金项目
国家自然科学基金资助项目(52277203,52277164) （52277203,52277164）
