Admittance spectroscopy was employed to investigate the electrical properties of buried GaSb homojunctions. A strong p-type surface layer was obtained in n-type GaSb bulk crystals through diffusion of Zn atoms. The acceptor impurities were introduced into Te-doped substrates by epitaxially growing a heavily p (Zn)-doped GaAs layer. Current-voltage investigation, after the removal of the GaAs cap layer, demonstrated the formation of the GaSb pn homojunction. However, the pn interface of the junctions resulted to be not due to the presence of Zn. In fact, secondary ion mass spectrometry pointed out only a small penetration depth of Zn atoms in the GaSb substrate (∼ 100 nm), whereas electron beam induced current investigation demonstrated that the pn junction interface was located more deeply into the substrate (∼ 1 μ m). Admittance spectroscopy and capacitance-voltage …