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

Abstract
High‐speed, 80‐μm‐diam, GaAs/Alx Ga1−x As pin 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 pin 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.