Photoelectric properties of photodiodes based on InAs/InAsSbP heterostructures with photosensitive-area diameters of 0.1–2.0 mm

The results of a study aimed at the development of high-efficiency photodiodes for the spectral range 1.5–3.8 $\mu$m with various photosensitive-area diameters in the range 0.1–2.0 mm are reported. Epitaxial techniques for the growth of InAs/InAsSbP photodiode heterostructures are developed. The distinctive features of the diodes are their high monochromatic current sensitivity $S_\lambda$ of up to 1.6 A/W at the peak of the spectrum, $\lambda$ = 3.0–3.4 $\mu$m, and the detectivity of the photodiodes, estimated by the experimentally measured noise level and the monochromatic current sensitivity, reaching at the spectrum peak a value of $D^*(\lambda_{\mathrm{max}}$, 1000, 1) = (0.6–12) $\times$ 10$^{10}$ cm Hz$^{1/2}$ W$^{-1}$ at $T$ = 300 K. The bulk component of the reverse dark current in the photodiodes under study is constituted by two components: diffusion- and tunneling-related, with a low density of reverse dark currents $j$ = (0.3–6) $\times$ 10$^{-1}$ A/cm$^2$ attained at a bias of $U$ = –(0.2–0.4) V. The photodiodes are characterized by the product $R_0 A$ = 0.4–3.2 $\Omega$ cm$^2$. With the diameter of the photosensitive-area increased within the range 0.1–2.0 mm, the specific detectivity of a photodiode increases by nearly a factor of 2, which is due to the weaker effect of surface leakage currents with its increasing diameter. The response time of diodes of this kind varies within the range 1–300 ns, which enables their use in open-space optical communication systems in the atmospheric-transparency window. Photodiodes with a large sensitive area (up to 2.0 mm), high specific detectivity, and high photosensitivity can be used to detect absorption bands and record the concentrations of such substances as methane, ether, N$_2$O, and phthorothanum.