Electroluminescence and photovoltaic effects of anodically fabricated metal/porous Si/Si sandwich structures based on ntype ultravioletporous Si

The use of silicon based light emitting diodes may completely solve the problem of low compatibility of optoelectronics elements and silicon chip. At present time the most suitable kinds of Si-LEDs are monocrystal and porous silicon avalanche LEDs. They have advantages such as long operation lifetime (> 10000 hours), continuous spectrum, which allows to filter RGB colors, operation voltages (< 12 V), extremely sharp voltage-current characteristic, nanosecond response time, and high high operation current densities (up to 8000 A/cm 2 in pulse mode). Rather low energy efficiency (< 1%) is not so significant for near to eyes (NTE) microdisplays. These advantages open a way to design a high performance and cost effective passive addressed microdisplays.

We report the realization of a bright and stable electroluminescent Schottky diode based on aluminum-porous silicon junction. White light, visible in normal daylight, is emitted when a reverse bias is applied to the device, promoting the junction breakdown. The device has a fast (100 ns) rise time of the light emission. An excellent stability, tested over more than one month of continuous operation at a high bias level, is achieved by the complete encapsulation of the active porous silicon under a transparent alumina layer. The external power efficiency of light emission is 0.01%.

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