Title :
Effect of p-doped overlayer thickness on RF-dispersion in GaN junction FETs
Author :
Jimnez, A. ; Buttari, D. ; Jena, D. ; Coffie, R. ; Heikman, S. ; Zhang, N.-Q. ; Shen, L. ; Calleja, E. ; Muñoz, E. ; Speck, J. ; Mishra, U.K.
Author_Institution :
Departamento de Ingenieria Electronica, Univ. Politecnica de Madrid, Spain
fDate :
6/1/2002 12:00:00 AM
Abstract :
Successive reactive ion etchings (RIE) were performed on the access regions of p/sup +/-n GaN JFETs. A decrease in the n-layer sheet resistance, with a consequent increase in I/sub DSS/ was detected after complete removal of the p-layer, due to a reduction in the n-layer depletion region. An increase in RF-dispersion was experienced, as a result of the progressive reduction of screening from surface-states originally provided by the overlying p-cap layer. No dispersion was detected before cap removal. A continuous increase in f/sub t/ and f/sub max/ was detected even before complete removal of the p-layer, due to virtual gate length reduction. It is expected that an optimized p-doped overlayer will provide current slump suppression without degradation in cutoff frequency or breakdown.
Keywords :
III-V semiconductors; gallium compounds; junction gate field effect transistors; semiconductor device breakdown; sputter etching; surface states; wide band gap semiconductors; GaN; GaN junction FET; RF dispersion; breakdown voltage; current slump; cutoff frequency; n-layer depletion region; n-layer sheet resistance; p-doped overlayer; p/sup +/-n junction; reactive ion etching; surface state screening; virtual gate length; Current slump; Degradation; Electric breakdown; Etching; Gallium nitride; JFETs; Molecular beam epitaxial growth; Passivation; Radio frequency; Silicon;
Journal_Title :
Electron Device Letters, IEEE
DOI :
10.1109/LED.2002.1004217
