The (-201) oriented single crystalline β-Ga2O3 epilayers were deposited on (0001) sapphire at 450°C by metalorganic chemical vapor deposition, and then annealed at 800°C in atmosphere. From the analyses by transmission electron microscopy and X-ray photoelectron spectroscopy, it was evident that the oxygen vacancies existed in the asdeposited epilayer and reduced after annealing. Due to the decrease in oxygen vacancy, the crystal quality of Ga2O3 epilayer was improved. Photoluminescence results indicated that the defect emissions in the as-deposited epilayer could result from surface states and point defects. The defect emissions decreased apparently after annealing, causing by the recombination of oxygen atoms with gallium atoms inside the Ga2O3. Moreover, the metal-semiconductor-metal photodetectors were fabricated with the as-deposited and annealed Ga2O3 epilayers, respectively. Current-voltage measurements revealed that the photodetector with annealed Ga2O3 epilayer had a lower dark current with 2-3 orders of magnitude than that fabricated with as-deposited Ga2O3 epilayer at the same bias voltage. The improved performance is attributed to the decrease in free electrons resulted from oxygen vacancies, leading to a lower current leakage.
|Title of host publication||Physics and Mechanics of New Materials and Their Applications|
|Publisher||Nova Science Publishers, Inc.|
|Number of pages||9|
|State||Published - 1 Dec 2013|