REDSHIFTING OF A BOUND-TO-CONTINUUM GAAS ALGAAS QUANTUM-WELL INFRAREDPHOTODETECTOR RESPONSE VIA LASER ANNEALING/

The effect of laser annealing on important detector characteristics su ch as dark current, spectral response, and absolute responsivity is in vestigated for bound-to-continuum GaAs/AlGaAs quantum-well infrared ph otodetectors (QWIPs) operating in the 8-12 mu m wavelength regime. A s et of experiments was conducted on QWIPs fabricated from both as-grown and laser-annealed multiple-quantum-well structures. Compared to the as-grown structure, the peak spectral response of the laser-annealed s tructure was shifted to longer wavelengths, though absolute responsivi ty was decreased by about a factor of two. In addition, over a wide ra nge of bias levels, the laser-annealed QWIPs exhibited a slightly lowe r dark current compared to the as-grown QWIPs, Thus, the postgrowth co ntrol of GaAs/AlGaAs quantum-well composition profiles by laser anneal ing offers unique opportunities to fine tune various aspects of a QWIP 's response. (C) 1997 American Institute of Physics.