Peculiarities of the MBE growth physics and technology of narrow-gap II-VI compounds

Experimental research and a crystallochemical consideration of the chemical interaction of the film and substrate components in the A(2)B(6)/GaAs heterostructure were carried out. It was found that surface faceting, twinning and breaking of stoichiometry of the growing structure can be explained by the excess of valent electrons at the A(2)B(6)/GaAs interface. The films were grown in a multichamber mercury cadmium telluride (MCT) MBE system with different compositions of the residual gas phase in different chambers. The MCT growth chamber is equipped with a system of molecular sources of original design and a built-in automatic ellipsometer. The used system of sources allows for growing MCT films without sample rotation, uniform in composition over the substrate area of 51 mm in diameter (the composition gradient does not exceed 0.002 cm(-1)). Because there is no substrate rotation, continuous measurements of film composition can be performed during growth, and structures with specified composition over thickness can be grown. The introduction of layers with a varying energy gap into the heteroepitaxial structure increases the carrier's lifetime up to 2 mu s for x = 0.22 (77 K). A model of defects, determining the electric parameters of MBE grown films in the presence of gallium sources, is suggested. Linear photoconductor arrays for the 8-12 mu m band with background limited parameters were fabricated from the grown MCT films. (C) 1997 Elsevier Science S.A.