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 D_T and the time constantτ_T 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×l0~(13)eV 1·cm~2 at an energy of 0.33 eV to 3.07×10~(11) eV~1·cm~2 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. 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. These electrons are trapped in the AlGaN barrier of AZO-gated HEMT after it has experienced significant gate bias stress, and then the electrons can be excited effectively after it has been illuminated by the light with a certain wavelengths.Furthermore, the trap state density D_T and the time constantτ_T 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 from 1.93 × 10 ~ (13) eV 1 · cm ~ 2 at an energy of 0.33 eV to 3.07 × 10 ~ (11) eV ~ 1 · cm ~ 2 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.