GaAs p-i-n photodiodes made by metalorganic chemical vapor deposition using tertiarybutylarsine and arsine

High-speed, 80-μm-diam, GaAs/Alx Ga1−x As p-i-n photodiodes having frequency response in excess of 7 GHz and internal quantum efficiency approaching 100% were fabricated by low-pressure metalorganic chemical vapor deposition (MOCVD) using both tertiarybutylarsine (TBA) and arsine. These are the highest performance MOCVD GaAs devices achieved with nonarsine sources and comparable to the best reported p-i-n photodiodes of similar size. Net carrier concentration of the undoped TBA GaAs was determined by capacitance-voltage analysis to be less than 5×1014 cm−3 . Photoluminescence measurements indicate that undoped TBA-grown Alx Ga1−x As (x=0.25) is also of excellent quality (FWHM=12 meV). Growth conditions leading to optimized devices were found to be similar for the two sources.