Oxidation by the UV & ozone process, nitridation by the nitrogen helicon-wave-excited plasma process, and the combination of these processes are applied to (100) GaAs wafers. An atomic force microscope, X-ray photoelectron spectroscopy, a transmission electron microscope, photoluminescence and electrical characteristics (current-voltage and capacitance-voltage) were used to analyze the influences of these processes on the structure and composition of the surfaces and the interfaces. Metal-insulator-semiconductor (MIS) diodes and Schottky diodes were fabricated in order to investigate the electrical influences of these processes. The oxidation slightly disorders GaAs surfaces. Nitridation of a bare surface creates about a 2nm-thick strongly disordered layer, which strongly deteriorates the electrical and photoluminescence characteristics. Nitridation of oxidated wafers (oxi-nitridation) forms firm amorphous GaON layers, which contain GaN, with very flat and sharp GaON/GaAs interfaces, where crystal disorder is hardly observed. It improves the current-voltage (I-V) and capacitance-voltage (C-V) characteristics and the photoluminescence intensity. Results of the structural and the electrical characterizations qualitatively coincide well with each other.

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The dependence of the leakage current in 1.3-m InGaAsP buried heterostructure (BH) lasers with p-n-p-n current blocking layers on well number, mesa width, and carrier density has been analyzed using a two-dimensional device simulator and compared with the electroluminescence (EL) emitted from InP layers. The analysis of the minority carrier flow reveals that the electron current flowing through the p-n-p-n current blocking layers is the dominant component of the leakage current. The measured EL intensity has two peaks at both sides of the nblocking layer apart from the active layer. The EL intensity decreases with increasing well number and carrier density of the p-blocking layer, and increases with increasing mesa width. These results are consistent with the simulations.

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