Studies of Electron Traps in Gallium Arsenide and Gallium Arsenide Phosphide by Deep Level Transient Spectroscopy.

摘要

System effects and data analysis for deep level transient spectroscopy (DLTS) have been examined and applied to study the deel levels in the GaAs-GaP system. Studies of typical DLTS systems using either the lock-in amplifier or the dual-channel boxcar averager are presented. The effects of non-zero gate width for the boxcar averager, phase angle adjustment for the lock-in amplifier, and response time of a typical commercial capacitance meter are investigated. Errors introduced in the measurements by these effects are calculated for typical cases. Measurements of gold level in silicon are presented, along with calculated corrections. We find the correction to be minimal in the boxcar-averager method, but significant in the lock-in amplifier approach. A DLTS system is described for measuring deep levels in diodes exhibiting large leakage currents. A capacitance bridge is used employing the diode to be tested along with a dummy diode of similar characteristics. The DLTS spectrum of a leaky GaAs planar diode is measured and compared to experimental results obtained with two standard DLTS systems . It is shown that measurements with the standard systems are impossible in certain temperature ranges because of overloading problems. The approach described here, however, gives the DLTS spectrum between 77 K and 300 K.