TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: In the method of forming gallium arsenide material, the deposition gas comprises arsine and gallium precursor gas at arsine/gallium precursor ratio of greater than or equal to 3. The gallium precursor gas comprises an alkyl gallium compound, preferably trimethylgallium or triethylgallium. The deposition gas further comprises aluminum precursor gas, and the gallium arsenide layer further comprises aluminum. The aluminum precursor gas comprises an alkyl aluminum compound, preferably trimethylaluminum or triethylaluminum. In the method of forming group III/V material, the deposition gas comprises nitrogen precursor gas, and group III/V layer includes nitrogen. The deposition gas further comprises a carrier gas including hydrogen, nitrogen, mixture of hydrogen and nitrogen, argon and/or helium. The gallium precursor gas comprises trimethylgallium, and the indium precursor gas comprises trimethylindium. The nitrogen precursor gas comprises hydrazine, methylhydrazine, dimethylhydrazine and/or their derivatives. The gallium precursor gas comprises trimethylgallium, the aluminum precursor gas comprises trimethylaluminum, the indium precursor gas comprises trimethylindium, and the phosphorus precursor gas comprises phosphine.    TECHNOLOGY FOCUS - INSTRUMENTATION AND TESTING - Preferred Method: In the method of forming gallium arsenide material, the deposition temperature is 550-900 degrees C or 600-900 degrees C. In the method of forming group III/V material, the deposition temperature is 600-800 degrees C. The processing system has internal pressure of 20-1000 Torr. EXAMPLE - Mixture of trimethylgallium and hydrogen gas (200 cc), was combined with hydrogen gas (2000 cc) and arsine (10 cc) to give deposition gas. The substrate was heated to a deposition temperature of 650-720 degrees C and exposed to the deposition gas. The group III/V material containing gallium and arsenic was deposited at greater than or equal to 60 mu m/hour to obtain gallium-arsenic deposited substrate.