Electrical and Optical Properties of InGaN/AlGaN DoubleHeterostructure Blue Light-Emitting Diodes

Electrical and optical properties of InGaN/AlGaN double heterostructure blue light-emitting diodes were investigated. Measurement of the forward bias current--voltage behaviour of the device demonstrated a departure from the Shockley model of a p--n diode, and it was observed that the dominant mechanism of carrier transport across the junction is associated with carrier tunnelling. Electroluminescence experiments indicated that there was a main emission band around 2.80 eV and a relatively weaker peak at 3.2 eV. A significant blueshift of the optical emission band was observed, which was consistent with the tunnelling character of electrical characteristics. Furthermore, the degradation in I-V characteristics and the low resistance ohmic short of the device were observed.