High Quality P-Type Mg-Doped β-Ga₂O_3-δFilms for Solar-Blind Photodetectors

The (2 01)-oriented Mg-doped β-Ga 2 O 3-δ films were grown on (0001)-sapphire substrates by pulsed laser deposition (PLD) at various oxygen partial pressures (P O,=10-40mTorr). The conductivity type of the as-deposited Mg-doped β-Ga2 O3-δ films is proved to be p-type according to the transfer characteristic curves of a top-gate field effect transistor (FET) and rectification curves of the Mg-doped/undoped β-Ga2 O3-δ junction. In addition, the two-terminal solar-blind photodetectors based on Mg-doped β-Ga 2 O3-δ films prepared at P O =30 mTorr exhibite a good optoelectrical performance with a low dark current of 0.19 pA at 10 V, a high I 254nm I dark ratio of 1.3× 104, fast rise (τ r1 =0.035 s and τ r2 =0.241 s) and decay (τ d1 =0.022 s and τ d2 =0.238 s) times. The present work indicates that the p-type Mg-doped β-Ga2 O3-δ films can be used in the third-generation ultraviolet photodetectors.