Both zinc oxide rods and zinc hydroxide slice were grown on gallium arsenide in the aqueous solution of zinc nitrate and hexamethylenetetramine. Incorporating with an appropriate concentration of nitric acid in the aqueous solution, the growth of zinc oxide rods or zinc hydroxide slice can be controlled. The cases with zinc hydroxide growth show very weak photoluminescence (PL). Much stronger PL can be obtained due to the transformation of zinc hydroxide into zinc oxide and quality improvement after thermal annealing. The case of only zinc oxide rod growth shows strong PL, but it shows optical degradation with a blueshift due to crystal cracking after thermal annealing. A reversible photoreductive deposition of copper ions (Cu2+) was used to evaluate the photocatalytic activity.