CHARACTERIZATION OF InAs-GaSb TYPE II SUPERLATTICES ROWN BY METAL ORGANIC CHEMICAL VAPOR DEPOSITION

摘要

It was observed that the conduction-band minimum of InAs is lower in energy than the valence-band maximum of GaSb. This will cause the non-rectification characteristic. Such unusual nonrectifying p-n junction is the direct consequence of interpenetra-tion between the GaSb valence band and the InAs conduction band, since the InAs-GaSb superlattices can have a band gap smaller than that of either constituent materials. InAs-GaSb superlattices have the modifiable band gap, but the absorption coefficient shall decrease rapidly when the period thickness is over 100 k(d1=d1). It has a good spectral response in 3-5 urn region, but bad in 8-14 ,m. The new proposal offered a normal incidence valence intersubband transition at -'lOu.m. It is potential to fabricate the long wavelength devices. In this paper, the InAs-GaSb superlattices were grown by MOCVD. The quality is determined by x-ray double crystal rocking curves. The period thickness is determined by High Resolution Transmission Electron Microscopy (HKTEM). The absorption spectra were obtained by Fourier Transform Infrared Spectroscopy (FTIR). Linear combination of atomic orbitals (LCAO) method and transform matrix were used to calculate the band structure and transition energy of InAs-GaSb superlattices.