Electron and hole traps in GaN p-i-n photodetectors grown by reactive molecular beam epitaxy

GaN p-i-n photodetectors grown on sapphire by reactive molecular beam epita xy have been characterized by measurements of room-temperature current-volt age (I-V), temperature-dependent capacitance (C-V-T), and deep level transi ent spectroscopy (DLTS) under both majority and minority carrier injection. Due to what we believe to be threading dislocations, the reverse I-V curve s of p-i-n photodetectors show typical electric-field enhanced soft breakdo wn characteristics. A carrier freeze-out due to the de-ionization of Mg-rel ated deep accepters has been found by C-V-T measurements. Three electron tr aps, B (0.61 eV), D (0.23 eV), and E-1 (0.25 eV) and one hole trap, H-3 (0. 79 eV) have been revealed by DLTS measurements. The photodetectors with low er leakage currents usually show higher responsivity and lower trap densiti es of D and E-1.