GaAs vapor-grown bipolar transistors

• Published in: Solid-state electronics Vol. 15; no. 1; pp. 81 - 84
• Main Authors: Nuese, C.J., Gannon, J.J., Dean, R.H., Gossenberger, H.F., Enstrom, R.E.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 1972
• ISSN: 0038-1101; 1879-2405
• DOI: 10.1016/0038-1101(72)90069-X

A study of several parameters which limit the current gain of GaAs bipolar transistors has led to the development of vapor-grown n- p- n GaAs transistors with reproducible current gains as high as 30 at room temperature and 15 at 300°C. These transistors have nearly flat I- V characteristics to voltages of about 50 V, and have a relatively weak dependence of current gain on temperature, varying by less than a factor of two between 25° and 300°C. The technology by which such transistors have been fabricated utilizes a NaOH : H 2O 2 chemical etch to expose (for contacting) portions of the 1 μm-thick middle (base) layer of a three-layered vapor-grown structure. With a post-fabrication HCl surface treatment transistor gains have been increased to values as high as 90, although such exceptionally high gains degrade to their pretreated values in about an hour due to the reversion of the GaAs surface to its pretreated condition. A photolithographic fabrication technology with a resolution of about 3 μm has been developed for use with the vapor-grown GaAs transistor structures.