Optoelectronic devices including heterojunction

Abstract

Embodiments of the invention generally relate to optoelectronic semiconductor devices such as photovoltaic devices including solar cells. In one aspect, an optoelectronic semiconductor device includes an absorber layer made of gallium arsenide (GaAs) and having only one type of doping. An emitter layer is located closer than the absorber layer to a back side of the device, the emitter layer made of a different material than the absorber layer and having a higher bandgap than the absorber layer. A heterojunction formed between the emitter layer and the absorber layer, and a p-n junction is formed between the emitter layer and the absorber layer and at least partially within the different material at a location offset from the heterojunction. The p-n junction causes a voltage to be generated in the device in response to the device being exposed to light at a front side of the device.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]Embodiments of the invention generally relate to optoelectronic semiconductor devices such as photovoltaic devices including solar cells, and methods for fabricating such optoelectronic devices.[0003]2. Description of the Related Art[0004]As fossil fuels are being depleted at ever-increasing rates, the need for alternative energy sources is becoming more and more apparent. Energy derived from wind, from the sun, and from flowing water offer renewable, environment-friendly alternatives to fossil fuels, such as coal, oil, and natural gas. Being readily available almost anywhere on Earth, solar energy may someday be a viable alternative.[0005]To harness energy from the sun, the junction of a solar cell absorbs photons to produce electron-hole pairs, which are separated by the internal electric field of the junction to generate a voltage, thereby converting light energy to electric energy. The generated voltage can be incre...

AI Technical Summary

Benefits of technology

[0007]Accordingly, there is a need for optoelectronic devices with increased efficiency and methods for fabricating such optoelectronic devices at reduced costs when compared to conventional solar cells.

Problems solved by technology

Nevertheless, the currently high cost of producing solar cells relative to the low efficiency levels of contemporary devices is preventing solar cells from becoming a mainstream energy source and limiting the applications to which solar cells may be suited.

These high temperature processes are generally expensive due to the excessive consumption of time and energy.

Also, the high temperature processes often damage sensitive materials contained within the photovoltaic device.

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