Electroluminescence device using indirect bandgap semiconductor

摘要

This invention provides an electroluminescence device comprising an indirect bandgap semiconductor layer, such as silicon or germanium, having a local conduction-band minimum at the Γ-point in an E-k diagram for using as a light emitting layer, and a direct bandgap semiconductor layer formed by a heterojunction on the indirect bandgap semiconductor layer for using as an electron supply means transporting electrons from a Γ-valley to a Γ-valley when a forward-biased voltage is applied, wherein a light emission is occurred by recombining the electrons transported to the Γ-valley of the indirect bandgap semiconductor layer with holes located at a valance band maximum of the indirect bandgap semiconductor layer.

主权项

1. An electroluminescence device, comprising:
an indirect bandgap semiconductor layer forming a Γ-valley with a local conduction-band minimum at a Γ-point in an E-k diagram; and a direct bandgap semiconductor layer formed by a heterojunction on the indirect bandgap semiconductor layer for supplying electrons to the Γ-valley of the indirect bandgap semiconductor layer, wherein the indirect bandgap semiconductor layer is a light emitting layer, wherein the direct bandgap semiconductor layer has a bandgap larger than the difference between a Γ-valley minimum of the indirect bandgap semiconductor layer and a valence band maximum of the indirect bandgap semiconductor layer, wherein the indirect bandgap semiconductor layer is doped with p-type impurities and the direct bandgap semiconductor layer is doped with n-type impurities, wherein the indirect and direct bandgap semiconductor layers have a contact portion for supplying an external power, respectively, wherein the indirect bandgap semiconductor layer emits a light by recombining electrons transported from a Γ-valley conduction band of the direct bandgap semiconductor layer to a Γ-valley conduction band of the indirect bandgap semiconductor layer with holes located at a valence band maximum of the indirect bandgap semiconductor layer when a forward-biased voltage is applied across a pn junction between the indirect and direct bandgap semiconductor layers through the contact portions, wherein the indirect bandgap semiconductor layer is formed on a p-type semiconductor substrate having an indirect bandgap as one body, wherein the contact portion of the indirect bandgap semiconductor layer is formed on the p-type semiconductor substrate as a p+ contact portion, the p+ contact portion surrounding around the indirect bandgap semiconductor layer, wherein the indirect bandgap semiconductor layer is a single crystal silicon (Si) or germanium (Ge), and wherein the direct bandgap semiconductor layer has a conduction band minimum larger than or equal to the Γ-valley minimum of the indirect bandgap semiconductor layer and has a valence band maximum smaller than the valence band maximum of the indirect bandgap semiconductor layer.