On the current transport across isotype heterojunctions investigated on InP-based BRS-lasers

An evaluation of the temperature resolved I-V characteristics in connection with corresponding I-V simulations of homojunction and heterojunction test diodes in the high current regime (>1000 A cm/sup -2/), where the minimization of the additional series resistances for the heterodiode is of crucial importance, is presented. Proper design of layer sequence, composition, and growth provides low series resistance for the heterodiode and high turn-on voltage for the homodiode. A detailed analysis is presented of the intrinsic series resistance of the laser heterodiode, which results from two regions: the transition between the upper p-GaInAs contact and the p-InP cladding layers (also valid for the homojunctions), and the transition between the updoped GaInAsP (1.55 mu m) active and lower n-InP buffer layers. In both isotype junctions the inherent band edge discontinuities for the majority carriers are detrimental at high current densities.<>