DOMINANCE OF TUNNELING CURRENT AND BAND FILLING IN INGAN ALGAN DOUBLE-HETEROSTRUCTURE BLUE-LIGHT-EMITTING DIODES/

Measurement of the room temperature forward bias current-voltage behav ior of InGaN/AlGaN double heterostructure blue light-emitting diodes d emonstrates a significant departure from the usual I-s exp(qV/nkT) beh avior where n is the ideality factor which varies between I and 2. The observed current-voltage behavior at room temperature may be represen ted as I=2.7x10(-11) exp(5.7V) which suggests a tunneling mechanism. M easurement of the electroluminescence for currents from 0.5 to 100 mA demonstrates that the emission peak shifts to higher energy while incr easing in intensity. The shifting peak spectra is due to band filling, a process which results from the injection of holes via tunneling int o an empty acceptor impurity band and vacant valence band tails. At cu rrents near 100 mA, a non-shifting band-to-band emission approaches th e intensity of the shifting peak spectra. The active layer of these di odes is codoped with both the donor Si and the acceptor Zn. (C) 1996 A merican Institute of Physics.