Solid State Science and Technology, Vol. 16, No 1 (2008) 181-187
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XPS STUDY OF pHEMT STRUCTURE CLEANED USING HCl, HF AND BOE
Hesly Afida Hashima, Asban Dolaha, Mohamad Deramanb, Hariyadi Soetedjoa,
Mohamed Razman Yahyaa and Abdul Fatah Awang Mata
aMENT, TM Research & Development Sdn. Bhd., Idea Tower I & II,
UPM-MTDC Lebuh Silikon, 43400 Serdang, Selangor.
bSchool of Applied Physics, Faculty of Science and Technology,
Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor.
Unetched and HCl, HF, BOE solutions (acid to water = 1:10 and 1:20) etched surface of GaAs top layer of GaAs based pHEMT samples were analyzed by XPS technique. It was found that the unetched sample consists of about 9-10% oxide (Ga-oxides and/or As-oxides) species whereas other etched samples consist of 5-8% oxide content. The optimum effect of removing oxide layer was shown by HCl: H2O (1:10) treatment, where about 40% of oxides content reduction was achieved. At this concentration the XPS spectra of this sample also shows that (a) oxide contribution to O 1s peaks only come from As elements, (b) the treated surface is an As-rich surface. This is consistent with the decreasing value of Ga/As ratio before and after HCl treatment.
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