Accession Number : ADA299530

Title :   Silicon-Based Light-Emitting Diodes.

Descriptive Note : Final rept. 1 Jul 92-31 Dec 94,

Corporate Author : SPIRE CORP BEDFORD MA

Personal Author(s) : Namavar, Fereydoon

PDF Url : ADA299530

Report Date : 05 MAY 1995

Pagination or Media Count : 67

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

Descriptors :   *SILICON, *LIGHT EMITTING DIODES, EMISSION, INJECTION, MEASUREMENT, MATERIALS, ELECTROLUMINESCENCE, GALLIUM ARSENIDES, PHOTOLUMINESCENCE, HETEROJUNCTIONS, LIGHT, EFFICIENCY, FABRICATION, ELECTROCHEMISTRY, TRANSPARENCE, ENERGY GAPS, EPITAXIAL GROWTH, ETCHING, NITRIDES, SURFACES, DEPOSITION, ELECTRONS, OXIDES, BROADBAND, QUANTUM EFFICIENCY, TIN, N TYPE SEMICONDUCTORS, ELECTRIC CURRENT, INDIUM, SPUTTERING, POROUS MATERIALS, P TYPE SEMICONDUCTORS, CONFORMAL STRUCTURES, ELECTROPLATING.

Subject Categories : Inorganic Chemistry
      Physical Chemistry
      Electrical and Electronic Equipment
      Electricity and Magnetism
      Optics

Distribution Statement : APPROVED FOR PUBLIC RELEASE