Detailed characterization of deep level defects in InGaN Schottky diodes by optical and thermal deep level spectroscopies

Abstract

Schottky diode properties of semitransparent Ag(4 nm)/Au(4 nm) metal stack on In0.2Ga0.8N were investigated and defect characterization was performed using capacitance deep level transient (DLTS) and optical spectroscopy (DLOS). DLTS measurements made on the In0.2Ga0.8N Schottky diodes, which displayed a barrier height of 0.66 eV, revealed the presence of two deep levels located at Ec-0.39 eV and Ec-0.89 eV with nearly identical concentrations of ∼1.2 × 1015 cm−3. Three deeper defect levels were observed by DLOS at Ec-1.45 eV, Ec-1.76 eV, and Ec-2.50 eV with concentrations of 1.3 × 1015cm−3, 3.2 × 1015cm−3, and 6.1 × 1016 cm−3, respectively. The latter, with its high trap concentration and energy position lying 0.4 eV above the valance band, suggests a possible role in compensation of carrier concentration, whereas the mid-gap positions of the other two levels imply that they will be important recombination-generation centers