Temperature-Dependent Electrical Characteristics and Low-Frequency Noise Analysis of AlGaN/GaN HEMTs

In this paper, we investigate the electrical characteristics of AlGaN/GaN HEMTs at the lowest temperature of 20 K. The measurement results indicate that the output current of the device decreases significantly with increasing temperature at temperature ranging from 40 K to 260 K, and the saturation drain current decreases by 19%. The gate leakage current rises slightly when the temperature increases. However, both the transfer and C-V characteristics indicate that the threshold voltage shift slightly in a negative direction as the temperature rises. In order to determine the physical mechanism of electrical characteristics change, the low-frequency noise (LFN) characteristics at different temperatures were measured and the density of traps was extracted. Finally, we consider that there are two competing mechanisms affecting the electrical characteristics of devices. The trap density reduction caused by temperature rise leads to threshold voltage's negative shift, while the drop of 2DEG mobility is the main reason for the decrease of output current.