ELECTRICAL MEASUREMENTS OF BANDGAP SHRINKAGE IN HEAVILY DOPED P-TYPE GAAS

Electron currents injected into p + -GaAs were measured by analyzing the collector current versus base-emitter voltage characteristics of n-p + -n GaAs homojunction transistors. This technique facilitates accurate determination of electron injection currents for p-type GaAs doped greater than 1020 cm-3. Previous experiments used a diode-based, sequential etch technique to demonstrate that so-called bandgap shrinkage effects substantially increase the electron current injected into p+-GaAs. However, the diode-based technique was limited to dopant concentrations ≤1019 cm-3. Using the homojunction transistor-based technique described in this paper, we report a similar enhancement of the electron current injected into p-type GaAs doped as heavily as 8 × 1019 cm-3. © 1990 AIME.