Kinetics of the Reaction Hi-<111>Ge

Experiments are described which appear to differentiate between mass transport and surface reaction kinetics in the open tube reaction of gaseous hydrogen iodide with <111> germanium surfaces. Surface limiting reaction behavior is not observed until average linear gas stream velocities in the neighborhood of 800,000 cm/min are attained. The limiting reaction rate for the etching reaction is described by the equation log Rf =-3.64 × 103/T°K + log PHI + 5.42, Rf having the dimensions mg/cm2 hr. The reaction order was found to be unity which together with other information suggested that the desorption of germanium iodides constitutes the rate-limiting step. Autodoping phenomena are examined in view of the speed of the etching reaction, and calculated rate data for probable deposition reactions are presented. © 1966, The Electrochemical Society, Inc. All rights reserved.