Analysis of the response time in high-temperature LWIR HgCdTe photodiodes operating in non-equilibrium mode

The paper presents the theoretical investigation of the active region parameters, especially the influence of thickness and doping, on the response time and current responsivity of high-temperature long wavelength infrared HgCdTe photodiodes operating at 230 K in non-equilibrium mode. Results of theoretical predictions of time constant were compared to the experimental data. The response time of the devices have been characterized using Nd:YAG laser, optical parametric generator with pulse width <25 ps and fast oscilloscope with suitable transimpedance amplifier as a function of detector design, temperature and bias. The reverse bias applied to the photodiode causes Auger-suppression and improve the performances of the devices. This way the response time decreases to the value below 1 ns at the good current responsivity increased to the value of about 6 A/W and what is a promising parameter in view of potential telecommunication applications. Due to the series resistance of electrical connections, the response time of the devices is mainly limited by RC constant while the calculations show that the time constant of the Auger suppressed structures should be limited by the drift time of carriers.