DLTS Analyses of GaN p-i-n Diodes Grown on Conventional and Patterned Sapphire Substrates

In this letter, we report the electrical characteristics of current-voltage, capacitance-voltage, and deep-level transient spectroscopy on the GaN p-i-n diodes with a 5- μm i-layer, which were grown on the conventional sapphire substrates (CSSs) and patterned sapphire substrates (PSSs) by metal-organic chemical vapor deposition. The GaN p-i-n diodes with PSS exhibit a wider diffusion region in the forward bias, two traps at 0.43 and 0.87 eV above the valence band, and a low trap concentration of ~ 5×10¹⁶ cm^-3, as compared with the GaN p-i-n diodes with CSS. These results show that the GaN p-i-n diodes grown on PSS have a better quality of epitaxial layers than those grown on CSS.