Electrical and Optical Characteristics of Indium Arsenide Junction Lasers

Abstract

Electrical and light emission characteristics of pulsed InAs junction lasers were studied at various temperatures ranging from liquid helium temperature to room temperature. The junctions were prepared by vapor diffusing Zn into Sn doped n-type wafers of InAs, with a donor concentration of 10 18 cm -3 . Data variation of capacitance with bias showed these to be abrupt junctions. At low injection currents, the current injection mechanism was determined to be photon-assisted tunneling. Gain and loss factors at 20.4°K were determined from the variation of threshold current with diode cavity length. An independent value of the gain factor was determined from the observed variation with current of the superradiantly narrowed line-width from a nonlasing structure. The time-resolved laser spectra shift to longer wavelengths with time during pulsed operation of the laser. The line shift results from joule heating of the diode, and follows the variation of bandgap of InAs with temperature. Mode confinement studies indicate that the mode confinement is due to the optical gain in the active region at the junction and that the active region extends to approximately a diffusion length on both sides of the junction.