Light emitting diodes based on anodically oxidized silicon/porous silicon heterojunction

An improved test device, based on the light emitting device (LED) presented in the following article (L. Pavesi, R. Guardini, P. Bellutti, Thin Solid Films 297 (1997) 272) is reported. The whole processing of the diode is CMOS compatible and the porous Si (PS) formation is at the end of the run. The idea of the LED is to exploit the doping selectivity of the silicon anodization by forming n+-type doped crystalline Si stripes floating over the porous silicon layer. Electrical injection is through the n+ stripes into the PS, i.e. through a Si/PS heterojunction. Here, the electrical and optical properties of the electrochemically oxidized LED are characterized. Anodic oxidation improves the LED performance both in terms of stability (more than 8 days under CW excitation) and efficiency (a factor 3 or higher with respect to the as-grown LED).