Epitaxial n+-Ge/p+-Si(0 0 1) heterostructures with ultra sharp doping profiles for light emitting diode applications

Abstract

The prototype light emitting diodes (LEDs) were fabricated from the n+-Ge/p+-Si(001) heterostructures grown by low-temperature Hot Wire Chemical Vapor Deposition. The n+-Ge epitaxial layers were heavily doped with P from a sublimation solid-phase GaP source. Abrupt profiles of the donor impurity concentrations at the n+-Ge/p+-Si heterojunctions were obtained. Negative differential resistance was observed in the current–voltage curves of the LEDs at forward bias. Electroluminescence (EL) related to the indirect (phonon-assisted) interband radiative optical transitions in the n+-Ge layers (from the l-valleys of the conduction band into the Г-point in the valence band) was observed at room temperature. The EL intensity increased with increasing P concentration in the n+-Ge layers.