Silicon-Based Light-Emitting Diodes.
Abstract
We have demonstrated the fabrication of heterojunction porous silicon visible light-emitting devices (LEDs). Our device consists of a heterojunction between electrochemically etched p-type porous silicon and indium-tin-oxide (ITO), a transparent n-type semiconductor which was deposited by sputtering. On the basis of three independent measurements, current-brightness, current-voltage, and current-temperature, our results indicate that observed electroluminescence (EL) originates from minority (electron) carrier injection, the basic mechanism operating in GaAs-based LEDs or other homojunction devices. Our finding indicates that EL should be possible with the same impressive efficiency levels as the photoluminescence (PL) which was observed for porous silicon. However, the quantum efficiency of present devices has been compromised because the contacting areas between wide bandgap materials and porous Si are only a very small portion of the total porous Si surface. Present techniques used for LED fabrication only provide a contact to the tip of the pores; therefore, most of the surface of the light-emitting porous Si region is inactive in EL. Conformal coverage of a transparent conductive wide bandgap material into porous Si would enhance the quantum efficiency. Atomic layer epitaxy (ALE) growth of GaN (side-wall epitaxy), or electroplating of a transparent conducting oxide could increase the contact area which would result in an enhancement of EL efficiency. jg p.3
Document Details
- Document Type
- Technical Report
- Publication Date
- May 05, 1995
- Accession Number
- ADA299530
Entities
People
- Fereydoon Namavar