Tunnel injection of minority carriers in semi-conductors
AssigneeCornell Research Foundation, Inc.
InventorJoseph M. Ballantyne
Life of this patent
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Abstract
Disclosed are multi-layer thin-film devices having adjacent insulator-semiconductor layers employing n-or-p-type semiconductors wherein a charge maintained at the insulator-semiconductor interface creates a depletion region that substantially suppresses tunneling of majority carriers while enhancing tunneling of minority carriers. When employed in a metal-insulator semiconductor (MIS) device wherein the semiconductor is a compound such as gallium arsenide (GaAs) or Cadmium Sulfide (CdS), such minority carrier injection substantially increases the luminescence efficiency.
Claims8
In a multilayer thin-film device having adjacent insulator and semiconductor layers and producing an increased luminescence efficiency, the improvement which comprises:
- means to maintain a charge near the insulator-semiconductor interface of proper polarity and sufficient magnitude to create a depletion region in said semiconductor layer that substantially reduces majority carrier tunneling from the conduction band of said semiconductor layer and enhances minority carrier injection into said semiconductor layer and the resulting luminescence.
A multilayer thin-film device for producing electroluminescence, comprising:
- a first layer of semiconductor material;
- means forming a depletion region at a first surface of said semiconductor layer;
- a second, thin-film layer of insulator material deposited on said first surface of said semiconductor layer;
- a third layer of metal material deposited on said insulator material;
- means for applying a bias voltage across said device, said bias voltage and said depletion region cooperating to produce band-bending in the energy band gap of said semiconductor adjacent the interface between said first and second layers to substantially reduce majority carrier tunneling from the conduction band of said first layer to said third layer, and to lower the voltage threshold for minority carrier tunneling into said first layer from said third layer to less than the band gap of said semiconductor material of said first layer whereby minority carrier tunneling is enhanced to produce improved electroluminescence.
Dependencies are inferred from the claim text.