The MOCVD system used is shown in Figure 1. This system consisted of a gas supplying system, a reaction chamber and a evacuation system. The gas supplying system had five temperature controlled ovens for controlling the temperature of the source precursor vessels. The pressures in the source vessels were monitored using pressure sensors. All of the stainless steel tubes connecting the gas supplying system to the reaction chamber were heated by temperature controlled ribbon heaters to prevent the solidification of the source materials inside the stainless steel tubes. The gas flow rates were precisely controlled using mass flow controllers. The reactor chamber was of a vertical type and was made of stainless steel. The inside diameter was around 300 mm. A 6 - 8 inch wafer could be loaded in this reactor. The susceptor was heated by a thermal heater and the temperature of the susceptor could be controlled precisely. When the wafers were loaded, the susceptor part was moved up and down using an air operation system. The reaction pressure in the reactor could be kept constant using an automatic throttle valve system. In the evacuation system, a mechanical booster pump and rotary pump were used. The exhaust gas was decomposed in a thermal furnace and released to the air.