Abstract
This paper is dedicated to the study of electrical and optical properties of four different doped 21.5 pairs AlAsSb/GaSb distributed Bragg reflectors lattice-matched to GaSb and designed for the fabrication of electrically pumped VCSELs emitting around 2.3 µm. Three different doping profiles have been carried out: n-bulk doping, n-delta doping and p-bulk doping. An n-type bulk doped Bragg mirror with step composition at GaSb/AlAsSb interfaces was also tested. The n-type bulk doped sample with sharp interfaces exhibited the best electrical properties, a voltage drop per pair of 25 mV and a specific resistance of 1 × 10−4 Ω cm2 at 1 kA cm−2. Moreover, optical losses as low as 5–10 cm−1 have been measured for n-type doped mirrors.