Thallium quantum dot photodetectors

Abstract

This work studies, theoretically, the thallium-based quantum dot photodetectors. The structures studied are $$In_{.93} Tl_{.07} Sb$$, $$In_{.33} Tl_{.67} P$$, $$In_{.85} Tl_{.15} As/GaAs$$, and $$In_{0.8} Tl_{0.2} N$$. Some parameters of the structures, like band-edge discontinuity, are not determined, yet. Structure parameters, energy subbands, absorption, and quantum efficiency (QE) spectra are calculated. High QE was obtained with the first structure which can be tuned at the required wavelength. High QE is obtained for the structures $$In_{.93} Tl_{.07} Sb$$ and $$In_{.33} Tl_{.67} P$$ when the junction depth is comparable to or less than the hole diffusion length $$(L_{p} )$$, while for the other two structures ($$In_{.85} Tl_{.15} As$$ and $$In_{0.8} Tl_{0.2} N$$) the junction depth must be larger than the hole diffusion length. The proposed photodetectors are covering the infrared range 3000–12000 nm which have an important applications.