Vol. 49, Issue 1, pp. 125-133
S-shaped current-voltage characteristic, UV LED
For InGaN/AlGaN/GaN ultraviolet (λ = 365 nm) light emitting diodes, the S-shaped current-voltage characteristic was observed at liquid nitrogen temperature due to the transition from single injection (electrons) to double (electrons and holes) injection. Initially only electron injection into the active region takes place and as the current is increased, the injection of holes starts. It has been found that at the voltage of the minimum of the negative differential resistance region, oscillations of the current, accompanied by increasing electroluminescence intensity arise, and the repetition rate of the oscillations increases with the direct current rise. The intensity of the main ultraviolet and yellow electroluminescence bands sharply increases with increasing current at negative differential resistance region due to the rise of holes injection.