Local field emission spectroscopy of InSb micrograins

Local electron density-of-state spectra and level parameters in indium antimonide (InSb) micrograins have been studied using a tunneling microscope in the field-electron emission regime. The activation energies $(\psi)$ of electron levels and electron lifetimes $(\tau)$ on these levels have been determined based on the correspondence of current–voltage characteristics to the probabilities of emission. Several local electron levels in a near-surface region of intrinsic ($i$-InSb) micrograins are identified with $\psi\sim$ 0.73, 1.33, 1.85, 2.15, and 5.1 eV and $\tau\sim$ 5 $\cdot$ 10$^{-8}$–3 $\cdot$ 10$^{-7}$ s, respectively. A physical model is proposed, according to which “light” electrons are localized due to the Coulomb interaction and their dimensional quantization takes place in the near-surface zone as determined by the effective mass, energy, and concentration of electrons and the radius of curvature of the micrograin surface.