Structural, electrical and phototransient characteristics of liquid phase epitaxial GaP based heterojunction for photodiode application

Heterojunction of GaP/p-Si device was successfully grown by liquid phase epitaxy. A structural characteristic of the heterojunction device was characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). X-ray peak broadening analysis was used to evaluate the crystallite size by using the Williamson-Hall (W-H) analysis. The capacitance-voltage (C-V) and current-voltage (I-V) characteristics were measured in the temperature range 300-400 M under dark condition. The dependence of C-2 on V is found to be almost linear which indicates that the type of the heterojunction is abrupt. The main junction parameters such as built-in potential (V-b), the donor carrier concentration (N-D) and the width of the depletion region (W) were extracted from C-V characteristics and studied as a function of temperature. The I-V characteristics of the heterojunction device exhibit moderate rectifying behavior which can be attributed to the formation of heterojunction interface. At lower voltages, the forward current of the device is found to obey the intrinsic thermally generated charge carriers. At relatively higher voltages, the current mechanism of the heterojunction is controlled by a space charge limited conduction mechanism device. The main parameters of the heterojunction device such as series resistance (R-s), shunt resistance (R-sh), the ideality factor (n) and the barrier height (Phi b) were determined from I-V characteristics. Photocurrent of the heterojunction device increases with increasing power intensity and the transient photocurrent results indicate that the photocurrent can be explained by continuous distribution of traps. (C) 2013 Elsevier Ltd. All rights reserved.