Electrical characterization of the InAlN/GaN heterostructures by capacitance methods

Abstract

This paper highlights the electrical characterization of 4 types of the Schottky structures prepared on InAlN/GaN epi-layer designed for HEMT's with the AlN buffer layer and semi-insulating 6H-SiC substrate, which have different mechanical strain due to different growth conditions, using capacitance-voltage and Deep Level Transient Spectroscopy methods (DLTS). The sudden fall of capacitance in the range of reverse voltage from -2.5 to -3.3 V is caused by heterostructure's interface depletion. According to the DLTS measurement it is highly probable that the similar system of defects is present in all samples. Parameters of 7 hole-like traps were identified. Three of them HT1 (1.48 eV) HT2 (1.06 eV) and HT4 (1.01 eV) are certainly present in two structures and one HT3 (1.24 eV) in three structure. The highest concentration of defects has structure with the highest mechanical strain (Strain Raman 2 GPa).