Reactive Etching of Ga sub x As sub y sup - by HCl.

The gas phase reactions of HCl with anionic gallium arsenide clusters, Ga sub x As sub y sup -, containing 2 to 6 atoms are presented. Reaction rates and product distributions for the primary, secondary, and tertiary reactions are tabulated. Isomeric structures are detected kinetically for five clusters (GaAs sub 4 sup -, Ga sub 2 As sub 3 sup -, GaAs sub 4 H sup -, Ga sub 4 As sub 2 sup -, and Ga sub 2 As sub 4 sup -). HCl etches Ga sub x As sub y sup - primarily by loss of GaCl to form Ga sub (x-1) As sub y H sup -. The primarily reaction products also react with HCl primarily by loss of GaCl. Formation of GaCl and, for some clusters, As sub 2 mimics the etching of bulk gallium arsenide by HCl at elevated temperatures.