Electronic properties of a single heterojunction in InSb/InAs quantum dot system

We report on electronic transport properties of a single InSb quantum dot free-standing on the surface of a binary InAs matrix. The samples under study were grown by liquid phase epitaxy method. Characterisation of the sample surface was performed using atomic force microscopy (AFM). Uniform high-density (1 × 1010 cm−2) coherent InSb quantum dots with a height of 3–4 nm and a diameter of 13–18 nm were obtained at T = 430 °C. It was established that the sample surface has been covered by 3 nm-thick oxide layer in ambient environment at room temperature. Unique method of measurement of local tunnel transport across a type II broken-gap InSb/InAs heterojunction was proposed and developed. Electrical characteristics were measured in a contact mode with average force F = 75 nN that is enough to get repeatable I–V characteristics through the InSb oxide layer and to avoid destruction of the heterostructure. I–V characteristics of the single uncapped InSb quantum dot were for the first time obtained.