Light emitting porous silicon diode based on a silicon/porous silicon heterojunction

A new structure is proposed to improve the external quantum efficiency of p orous silicon (PS) light emitting diodes (LED). It is based on a heterojunc tion between n-type doped silicon and PS. The heterojunction is formed due to the doping selectivity of the etching process used to form PS. The impro vement of the proposed LED structure with respect to usual metal/PS LED is demonstrated. This is thought to be due to a different injection mechanism for which carriers are injected directly into conduction band states. Anodi c oxidation experiments show further improvements in the LED efficiency. (C ) 1999 American Institute of Physics. [S0021-8979(99)07123-6].