JOURNAL OF THE KOREAN PHYSICAL SOCIETY, v.58, no.5, pp.1365 - 1368
A Si-doped GaN thin film with a carrier concentration of 1.13 x 10(19) cm(-3) was grown on a sapphire substrate by using metal-organic chemical vapor deposition (MOCVD). An inorganic/organic heterojunction was fabricated by spin-coating a p-type polymer poly(3, 4-ethylenedioxythiophene): poly(styrenesulphonic acid) (PEDOT:PSS) on the n-type GaN thin film. The current-voltage (I-V) characteristic of the heterojunction showed diode-like behavior. The I-V characteristic was examined in the framework of the thermionic emission model. The ideality factor and the barrier height (Phi(b)) were 12 and 0.5 eV, respectively. There is a discrepancy in the value of the ideality factor compared to the value predicted by the Sah-Noyce-Chockley theory. The higher value of the ideality factor is attributed to the existence of trap-assisted tunneling, carrier leakage, and multiple surface channels clue to excessive Si doping.