Growth Rate and Surface Morphology Studies in the GeCl[sub 4]-H[sub 2] System

Abstract

Growth rate studies of the GeC14-H2 reaction are reported for an epitaxial system. The experimentally observed deposition rates are described in terms of a "quasi-equilibrium" model in which only a limited portion of the gas achieves equilibrium composition. Smooth surfaces are obtained under conditions where epitaxial growth appears to be mass transport controlled. For any given Ge concentration, the observed dependence of growth rate on temperature and substrate orientation indicates that a surface limitation controls growth at lower growth temperatures. When this condition prevails, structured deposits result. Structureless surfaces are favored by operating at high temperatures and low Ge concentrations.

Growth Mechanism for Germanium Deposition near a SiO[sub 2]-Ge Boundary

“…2 and 3 of Ref. (15). Thus, we conclude that a surface rate limitation probably has not been reached in the neighborhood of the ridge, although any increase in transport rates unavoidably shifts the system closer to that condition.…”

“…Ge/H2 ----3.6 • 10-4; linear gas stream velocity, 175 cm/min; growth times were constant at 11 min. Under these conditions the growth rate was constant at 0.099 ~m/min (15), and ridge growth immediately adjacent to the oxide was noted for all samples. Ridge measurement.--Vertical profiles of the ridge were taken across the shorter dimension of the pads employing a stylus gauge.…”

“…The surface flux at the oxide-Ge boundary is prescribed by a first-order chemical reaction dn --Ds -~x : ksn, x : l [3] where ks is a reaction rate constant. We assume a first-order reaction since such is the case for growth on a bare Ge wafer (15). Defining a mean diffusion distance (24) Xs = (Ds ~)1/2, a symmetric solution of [2] and [3] is easily obtained Turning now to the Ge ridge, the existence of such a smooth (i.e.…”

Development of ultra pure germanium epi layers for blocked impurity band far infrared detectors

“…The HCI formed may, in turn, react with the solid Ge to form other gaseous species detected in the GeC14-H 2 system [60], such as GeC12 and GeCI 3. The situation in the reactor is considerably more complex than that suggested by the overall reaction…”

“…Other investigators [67][68][69][70][71][72] examined growth conditions and surface morphology for different crystallographic orientations. Silvestri [60] observed that at deposition temperatures from 600-850°C, the deposition rate (less than about 2x 10-3 Torr) epitaxial growth of Ge was observed on Ge (100) surfaces, whereas at higher partial pressures, etching of the Ge occurred. They…”