In this paper, inductively coupled plasma etching of InSb material has been investigated using methane–hydrogen chemistry. Plasma conditions were first studied in terms of bias autopolarization, partial methane quantity in a CH4/H2 mixture and chamber pressure. The surface morphology of the etched samples was analyzed using an atomic force microscope, scanning electron microscope and x-ray photoelectron spectrometry (XPS) measurements. The results highlight the difficulties in removing etching products related to In, and the surface roughness is mainly correlated with the methane ratio in the mixture. The best surface stoichiometry, with a surface roughness of 7 nm and an etch rate of 110 nm min−1, was obtained with the addition of argon. To evaluate the feasibility of high performance infrared photodiodes, InSb monopixels were fabricated by dry etching, electrically characterized under illumination and compared with devices obtained by wet etching.
Deep levels in InSb crystals used for photodiodes have been investigated. An electron trap was found at 0.10 and 0.12 eV below the conduction band in n-type undoped and Te-doped InSb, respectively. A hole trap was observed in both specimens and its level in a Te-doped specimen was estimated to be 0.032 eV above the valence band. The distribution profile and electron capture cross section of the electron traps were also measured.
In this work we demonstrate experimentally the dependence of InSb crystal structure on the ratio of Sb to In atoms at the growth front. Epitaxial InSb wires are grown by a self-seeded particle assisted growth technique on several different III–V substrates. Detailed investigations of growth parameters and post-growth energy dispersive x-ray spectroscopy indicate that the seed particles initially consist of In and incorporate up to 20 at.% Sb during growth. By applying this technique we demonstrate the formation of zinc-blende, 4H and wurtzite structure in the InSb wires (identified by transmission electron microscopy and synchrotron x-ray diffraction), and correlate this sequential change in crystal structure to the increasing Sb/In ratio at the particle–wire interface. The low ionicity of InSb and the large diameter of the wire structures studied in this work are entirely outside the parameters for which polytype formation is predicted by current models of particle seeded wire growth, suggesting that the V/III ratio at the interface determines crystal structure in a manner well beyond current understanding. These results therefore provide important insight into the relationship between the particle composition and the crystal structure, and demonstrate the potential to selectively tune the crystal structure in other III–V compound materials as well.
A series of shock-recovery experiments on InSb single crystals along the (100) or (111) axes up to 24 GPa were performed using flyer plate impact. The structures of recovered samples were characterized by X-ray diffraction (XRD) analysis. According to calculated peak pressures and temperatures, and phase diagram for InSb, the sample could undergo phase transitions from zinc-blende structure to high-pressure phases. However, the XRD trace of each sample corresponded to powder pattern of InSb with zinc-blende structure. The XRD trace of each sample revealed the absence of additional constituents including metastable phases and high-pressure phases of InSb except for samples shocked around 16 GPa. At 16 GPa, in addition to zinc-blende structure, additional peaks were obtained. One of these peaks may correspond to the Cmcm or Immm phase of InSb, and the other peaks were not identified.