Effects of heavy impurity doping on electron injection in p+-n GaAs diodes

Measurements of electron injection currents in p+-n diodes are presented for a range of p-type dopant concentrations. A successive etch technique was used to characterize the electron injection current in terms of the product (noDn). Measurements are presented for Zn-doped GaAs solar cells with p-layer hole concentrations in the range 6.3×1017−1.3×1019 cm−3. The results demonstrate that so-called band-gap narrowing effects substantially increase the injected electron current in heavily doped p-type GaAs. These heavy doping effects must be accounted for in the modeling and design of GaAs solar cells and heterostructure bipolar transistors.