P. Jayavel

Enhancement of the quality of InAsSb epilayers using InAsSb graded and InSb buffer layers grown by hot wall epitaxy

We have investigated the structural and electrical properties of InAsxSb1−x epilayers grown on GaAs(0 0 1) substrates by hot wall epitaxy. The epilayers were grown on an InAsSb graded layer and an InSb buffer layer. The arsenic composition (x) of the InAsxSb1−x epilayer was calculated using x-ray diffraction and found to be 0.5. The graded layers were grown with As temperature gradients of 2 and 0.5 °C min−1. The three-dimensional (3D) island growth due to the large lattice mismatch between InAsSb and GaAs was observed by scanning electron microscopy. As the thicknesses of the InAsSb graded layer and the InSb buffer layer are increased, a transition from 3D island growth to two-dimensional plateau-like growth is observed. The x-ray rocking curve measurements indicate that full-width at half-maximum values of the epilayers were decreased by using the graded and buffer layers. A dramatic enhancement of the electron mobility of the grown layers was observed by Hall effect measurements.

Growth and Characterization of InAs x Sb1−x Bulk Crystals and Growth Rate Measurements

InAs x Sb1−x is an important material to fabricate detectors in the mid wavelength and long wavelength infrared region. The wavelength and the lattice constant for InAs x Sb1−x can be tuned in the range of 6.8 µ m–3.5 µ m and 6.478–6.058Å by adjusting the arsenic composition. InAs x Sb1−x crystals were grown by the vertical rotational Bridgman technique using GaAs (001) single crystal seed. Growth parameters such as temperature, period, ampoule design modification and cooling rate were analysed and used. A cooling rate of 0.25°C/hr is employed and the temperature of the growth region is carefully selected by suitably varying the temperature program/profile. Thermal pulse striations have been introduced inside the crystal during growth and etching technique was used to determine the real growth rate of the crystal. The chemical homogeneity and infrared transmittance analysis were carried out on the grown crystals.

Influence of Te impurity on morphology of GaSb epilayer grown on GaSb (001) patterned substrate by liquid phase epitaxy

We have studied the effect of Tellurium (Te) impurity on morphology of GaSb epilayer grown on GaSb (001) circular patterned substrates by liquid phase epitaxy. The results of the Te doped GaSb epilayers have been compared with the undoped GaSb epilayer under identical growth conditions. After the addition of Te impurity up to 0.12mol% in the starting solution, it is observed that a (311)B facet is formed instead of a (111)B facet while there is no such transition in the (111)A facet. The reason for the transition of the (111)B facet to the (311)B is discussed and an atomic model is proposed to explain the transition of the facet. The cross-sectional (110) plane of the Te doped GaSb epilayer after stain etching in a permanganate etchant reveals that two boundaries are separating differently doped upper and lateral regions of the epilayer. Furthermore, a few Te impurity striations are observed in the lateral region of the epilayer but none are found in the upper region. The growth time dependence of the mor...