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Influence of dry etch conditions on the properties of Schottky contacts to n-GaAs

Einfluss der Trockenätzbedingungen auf die Eigenschaften von Schottkykontakten auf n-GaAs

Materials Research Society -MRS-:
2nd International Conference on Electronic Materials '90. Proceedings
pp.283-288 : Abb.,Tab.,Lit.
International Conference on Electronic Materials <2, 1990>
Conference Paper
Fraunhofer IAF ()
C-V measurements; C-V Messungen; CF4; CHF3; n-GaAs; reactive ion etching; reaktives Ionenätzen; Schottky contacts; Schottkykontakte

Changes in the electrical properties of n-GaAs Schottky contacts due to reactive ion etching (RIE) have been examined for RIE processes using CF sub 4 and CHF sub 3, respectively. For this purpose RIE conditions closely related to those applied in our device fabrication scheme have been used. Our results prove that soft RIE processing using CF sub 4 yields only negligible changes in the various diode parameters. Also the doping profile as derived from C-V measurements for reverse bias does not show any degradation. In contrast even soft RIE processing with CHF sub 3 results in large variations of e.g. barrier height (decrease about 200 mV), zero bias capacitance (decrease about 120 pF). Furthermore substantial degradation of the doping profile is observed. From additional experiments using CHF sub 3 dry etching in the gate region of GaAs/AlGaAs heterostructure field effect transistors (HFETs) a shift in threshold voltage of about 850 mV towards more positive values is obtained while th e channel resistance increases from 76 to 1500 Ohms as compared to our standard gate recess.