Growth Mechanism of Vapor Deposited Germanium Films

Abstract

Direct microscopic observation of the movement of growth steps during chemical vapor deposition of epitaxial layers of germanium on germanium substrates, in an open tube reactor, has been employed to study growth mechanisms operative in this system. The reaction studied was the disproportionation of germanium diiodide: 2GeI2false(normalgfalse)=normalGefalse(normalsfalse)+GeI4false(normalgfalse) . Rate of step movement has been measured as a function of step height, substrate temperature, iodide pressure, gas flow rate, and other growth variables. In addition, transpiration measurements have been made to determine the actual partial pressures for gaseous species produced at various sites in the open‐tube flow system. The predominant stepped growth features observed on (111) planes were triangular pyramids. They are shown to be quite minor deviations from the (111) plane, the slope of the side for a typical pyramid being at most 1 in 30. A maximum in rate of step movement has been found with the germanium seed near 360°C, and observable step movement was detected in a narrow temperature range about this optimum temperature. From the observed influence of step height and iodide pressure on rate of step movement it is suggested that growth depends on processes occurring directly at step sites. At high iodide pressure two‐dimensional nucleation of germanium on terrace portions may occur, resulting in an increased concentration of crystalline defects.

Dopage par As de couches épitaxiées de Ge sur substrats Ge et GaAs

“…-réactivité de ASI3 en présence de Gel2 AsI3(g) + 3/2 GeI2(g) ~ As(s) + 3/2 GeI4(g) . (4) Nous allons déterminer la fraction fi de AsI3 qui est réduit par Gel2 suivant la réaction (4). Pour Fig.…”