GaSb/GaAlAsSb heterostructure photodiodes for the near-IR spectral range

GaSb/GaAlAsSb uncooled photodiodes for the 1.1–1.85 $\mu$m spectral range are fabricated and studied. A unique method for the growth of GaSb from lead solution-melts makes it possible to obtain a low carrier concentration in the active region: $n$ = 2 $\times$ 10$^{15}$ cm$^{-3}$. The capacitance of the photodiodes is 70–110 pF for a sensitive -area diameter of 300 $\mu$m and 150–250 pF for a diameter of 500 $\mu$m. The photodiodes are characterized by a high (for GaSb devices) spectral sensitivity $S_\lambda$ = 0.95 A/W at the maximum, a relatively low reverse dark current density $j$ = (4–9) $\times$ 10$^{-3}$ A/cm$^2$ at $U_{\operatorname{rev}}$ = 1.0–2.0 V, and high-speed performance (response time 5–10 ns).