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

A new structure is proposed to improve the external quantum efficiency of porous silicon (PS) light emitting diodes (LED). It is based on a heterojunction 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 improvement 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. Anodic oxidation experiments show further improvements in the LED efficiency. (C) 1999 American Institute of Physics. [S0021-8979(99)07123-6]

Optical properties and photonic bands of si-based photonic crystals

A complete characterization of the photonic band structure is obtained by means of variable angle-reflectance and phase-sensitive techniques. The experimental results are compared to calculated reflectance and photonic band dispersion over a wide spectral range, and selection rules for the excitations of photonic modes in the crystal are obtained according to a symmetry analysi