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Self-assembled InAs quantum dots (QDs) embedded in an InAlGaAs matrix were grown on an InP (001) using a solid-source molecular beam epitaxy and investigated using transmission electron microscopy (TEM) and photoluminescence (PL) spectroscopy. TEM images indicated that the QD formation was strongly dependent on the growth behaviors of group III elements during the deposition of InAlGaAs barriers. We achieved a lasing operation of around 1.5 µm at room temperature from uncoated QD lasers based on the InAlGaAs-InAlAs material system on the InP (001). The lasing wavelengths of the ridge-waveguide QD lasers were also dependent upon the cavity lengths due mainly to the gain required for the lasing operation.

The light output power (LOP) of vertical-type GaN-based light emitting diodes (LED) with surface roughness (texture) can be changed by texture size, density, and thickness of GaN film or by the combined effects of texture formation and thickness of GaN film. We have investigated these changes experimentally and note that the enhancement of the LOP by a factor of 2.4 can be improved with optimum texturing parameters as compared to that without texturing. In addition, the LOP of GaN-based LEDs under the same texture density increase slightly as thickness of GaN film decreases. Base on these results, we have evidently demonstrated that the enhancement factors of LOP are related to the correlation between texture size (density) and thickness of GaN film.

Zinc oxide thin films were grown in a temperature range of 70 to 180oC by means of plasma enhanced atomic layer deposition (PEALD) for the first time. The films have growth rate of 1.9Aå/cycle. The XRD patterns showed more or less random orientation of ZnO films grown by PEALD, but the reduced plasma power resulted in preferred (002) orientation of films at 150oC. The sheet resistivity of films grown with oxygen plasma was too high to measure with 4 point probe and Hall measurement system. The difference of electrical property between PEALD and H2O-based ALD films is attributed to a different O/Zn atomic ratio.