Optical properties of GaSb alloys and photodiodes grown by liquid-phase epitaxy

The carrier concentration of GaSb epitaxial layers grown from Sb-rich solutions by liquid-phase epitaxy is controlled by replacing nominally undoped GaSb by Te-doped polycrystalline GaSb to suppress or compensate the background hole concentration. The dependence of the 10 K photoluminescence peak wavelength and intensity on the doping level of the Te-compensated GaSb layers has been investigated. The absorption spectra are examined as a function of carrier concentration. Low-dopant-concentration p-type GaSb samples exhibit the band gap shrinkage with increasing hole concentration, while the lightly Te-doped n-type. GaSb samples exhibit a band gap increase due to the Burstein-Moss shift with increasing electron concentration. By using Te-doped GaSb layers with an electron concentration of 5.6 x 10(15) cm(-3) the fabricated GaSb photodiodes exhibit a low dark current of 2 mu A at -5 V, a high breakdown voltage of 28.7 V at 20 mu A, and a maximum photoresponsivity of 0.55 A/W with an external quantum efficiency of 40% at 1.72 mu m wavelength. (C) 1996 American Institute of Physics.