Abstract: According to a disclosed embodiment, a gas is supplied at a certain partial pressure for a chemical reaction with a top surface of a base in a transistor. The top surface of the base is heated to a certain temperature to promote the chemical reaction. For example, the gas can be oxygen, the base can be an epitaxial single crystal silicon-germanium base of a heterojunction bipolar transistor (“HBT”), and the chemical reaction can be oxidation of the silicon in the top surface of the silicon-germanium base. In one embodiment of the invention, the partial pressure of oxygen is maintained at 0.1 atmosphere and the top surface of the base is heated using rapid thermal processing (“RTP”) to a temperature of 500° C. The chemical reaction forms a dielectric layer on the top surface of the base. For example, using oxygen as stated above, a dielectric layer of silicon oxide (“interfacial oxide”) is formed.

Abstract: A gas is supplied at a certain partial pressure for a chemical reaction with a top surface of a base in a transistor. The top surface of the base is heated to a certain temperature to promote the chemical reaction. For example, the gas can be oxygen, the base can be an epitaxial single crystal silicon-germanium base of a heterojunction bipolar transistor (“HBT”), and the chemical reaction can be oxidation of the silicon in the top surface of the silicon-germanium base. The partial pressure of oxygen is maintained at 0.1 atmosphere and the top surface of the base is heated using rapid thermal processing (“RTP”) to a temperature of 500° C. The chemical reaction forms a dielectric layer on the top surface of the base. For example, using oxygen as stated above, a dielectric layer of silicon oxide (“interfacial oxide”) is formed. Controlling the thickness and density of the interfacial oxide causes the gain of the transistor to be as desired.