AlAsSb/GaSb doped distributed Bragg reflectors for electrically pumped VCSELs emitting around 2.3 µm

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 cm 2 at 1 kA cm −2 . Moreover, optical losses as low as 5–10 cm −1 have been measured for n-type doped mirrors.