Quality improvement of oxidized-GaAs/n-GaAs structure by nitrogen plasma treatment

GaAs-MISFETs With Insulating Gate Films Formed by Direct Oxidation and by Oxinitridation of Recessed GaAs Surfaces

“…Hara et al reported improved capacitance-voltage (C-V) characteristics of an oxidized GaAs-MIS diode by subjecting it to a helicon-waveexcited N plasma treatment [9], although Trivedi et al reported on N plasma damage of an AlGaAs-InGaAs-GaAs system [10]. Our experimental results demonstrate that N plasma nitridation after the UV and ozone oxidation forms a good quality GaAs-insulator interface with very little crystallographic disorder and improves both the electrical and the photoluminescence performance [11]- [13]. In order to check whether the beneficial effect of the N plasma nitridation is reproduced in a device fabrication process, we simultaneously fabricated GaAsMOSFETs (oxidation by UV and ozone only) and GaAs-MISFETs (N plasma after the UV and ozone oxidation) and compared their performance.…”

Fabrication of GaAs MISFET with nm-thin oxidized layer formed by UV and ozone process

“…Moreover, nitridation of the oxide film solves insufficient increase of high-frequency capacitance at a forward bias, which Passlack et al theoretically derived as a sign of unpinning [14]. Frequency dependence of C-V curves of the Ni/GaAs-oxide/n-GaAs system, in a frequency range of kHz MHz, is small [12].…”

“…The RF response of the GaAs MISFETs was measured, showing the current cutoff frequency of 6 GHz and the maximum oscillation frequency of 8 GHz with 1-m-long gate length and 8-nm-thick oxidized layer. The quality improvement of the oxide layer is now being studied [12] and the results will be presented elsewhere along with some dielectric properties of the oxide layer. Dr. Iiyama is a member of the IEICE and the Japan Society of Applied Physics.…”

“…The leakage current increased with the oxidation time up to 120 min, and then decreased by longer oxidation time. Our recent work [12], [13] on the C-V characteristics of Ni/GaAsoxide/n-GaAs, Ni/GaAs-oxinitride/n-GaAs, etc, suggests that the deep levels are positively charged under the reverse bias condition, and then trap electrons when the bias approaches the flat-band voltage. Moreover, nitridation of the oxide film solves insufficient increase of high-frequency capacitance at a forward bias, which Passlack et al theoretically derived as a sign of unpinning [14].…”

Structural and Electrical Characterization of Oxidated, Nitridated and Oxi-nitridated (100) GaAs Surfaces

“…15) Recently, we studied the nitridation of bare-and oxidated-GaAs (100) wafers by N 2 plasma and found their favorable influences on the structural and the electrical properties, when applied to oxidated GaAs surfaces. 16,17) In this paper, we report on the results of structural and electrical characterization of oxidated-, nitridated-, and oxi-nitridated-GaAs (100) wafers accomplished by using an atomic-force microscope (AFM), X-ray photoelectron spectroscopy (XPS), a transmission electron microscope (TEM), photoluminescence, and current-voltage (I-V) and capacitance-voltage (C-V) methods, and demonstrate that a long-time oxidation creates a nearly atomic flat oxide/semiconductor interface, nitridation of a bare GaAs surface creates a strongly disordered interface layer and deteriorates photoluminescence and electrical performances, and nitridation of an oxidated-GaAs wafer drastically reduces As of the oxide layer and converts it into a firm amorphous GaON layer, recovers disorder near the interface, and improves the photoluminescence and the electrical performances.…”