Electrical Characteristics of p–i–n Mesa-Photodiodes Based on InGaAs/InP Heterostructures

The current–voltage and capacitance–voltage characteristics of InGaAs/InP heterostructure p-i-n photodiodes fabricated by mesa technology have been studied. Photodiodes of circular configuration differ in active region diameter from 0.05 to 2.5 mm. All measurements are performed in the dark at room temperature using the probe method on a wafer with ready-made devices. Data are obtained on dark currents (leakage currents), I_dark, which are interpreted in terms of the surface and bulk currents in p–i–n photodiodes of various sizes. In the absorbing layer of the InGaAs/InP photodiode heterostructures, the concentration profiles N_D(x) are assessed for the first time by the nondestructive CV method and are compared with the electrochemical profiling data. It is shown that for the most part of the heterostructure i-layer the two methods are complementary.