High-frequency capacitance-voltage measurement of plasma-enhanced chemical-vapor-deposition-grown SiO2/n-GaN metal-insulator-semiconductor structures

This work reports on the high-frequency capacitance-voltage (C-V) measureme nts of metal-insulator-semiconductor structures fabricated by depositing Si O2 film on an n-type GaN epitaxial layer. The SiO2 film was grown by plasma -enhanced chemical vapor deposition at 310 degreesC, and the GaN layer was grown by low-pressure metalorganic chemical vapor deposition on a sapphire substrate. High-frequency C-V measurements have been carried out in darknes s with different bias ranges and sweep rates. With a bias between +/- 20 V, the small flatband shift and the very small hysteresis indicate that the i nterface trap concentration in the sample is low, and the interface state d ensity is 2.1x10(11) eV(-1) cm(-2). However, a pronounced increase of hyste resis with an extended bias range was observed. When the bias is over +/- 5 0 V, the increase of the hysteresis is much larger, indicating the nonunifo rm distribution of different slow deep states in the structure. The extract ed interface state density is in the range of 10(12) eV(-1) cm(-2). (C) 200 1 American Institute of Physics.