Photoresponse and trap characteristics of transparent AZO-gated AlGaN/GaN HEMT

• Published in: Chinese physics B Vol. 25; no. 10; pp. 525 - 528
• Main Author: 王冲 赵梦荻 何云龙 郑雪峰 张坤 魏晓晓 毛维 马晓华 张进成 郝跃
• Format: Journal Article
• Language: English
• Published: 01.10.2016
• ISSN: 1674-1056; 2058-3834
• DOI: 10.1088/1674-1056/25/10/108504

AZO-gated and Ni/Au-gated AlGaN/GaN HEMTs are fabricated successfully,and an excellent transparency of AZOgated electrode is achieved.After a negative gate bias stress acts on two kinds of the devices,their photoresponse characteristics are investigated by using laser sources with different wavelengths.The effect of photoresponse on AZO-gated electrode device is more obvious than on Ni/Au-gated electrodes device.The electrons are trapped in the AlGaN barrier of AZO-gated HEMT after it has experienced negative gate bias stress,and then the electrons can be excited effectively after it has been illuminated by the light with certain wavelengths.Furthermore,the trap state density DT and the time constantτT of the AZO-gated Schottky contact are extracted by fitting the measured parallel conductance in a frequency range from10 kHz to 10 MHz.The constants of the trap range from about 0.35 μs to 20.35 μs,and the trap state density increased from1.93×l013eV 1·cm2 at an energy of 0.33 eV to 3.07×1011 eV1·cm2 at an energy of 0.40 eV.Moreover,the capacitance and conductance measurements are used to characterize the trapping effects under different illumination conditions in AZO-gated HEMTs.Reduced deep trap states’ density is confirmed under the illumination of short wavelength light.