Characterisation and SILVACO modelling of Photovoltaic devices based on the InGaAs-InAlAs material systems

The use of solar energy is currently the best solution to the world energy problem and in particular the use of semiconductor cells is highly desirable as they permit direct conversion to electrical energy with no maintenance required. However, their efficiency is limited and that has resulted in the construction and deployment of solar arrays spanning several, sometimes hundreds of square meters. The search for advances in semiconductor design and fabrication has lead to the development of tandem multijunction cells using complex monolithic structures. Their high level of efficiency allows significant reduction in array sizes. Development of such designs will open up new areas in high end applications such as space and in power critical applications. In this work new methods for developing advanced solar cells based on the InGaAs-InAlAs material systems are investigated. We present the electrical and optical properties of several p-i-n diode structures, using compressively strained, lattice matched and strain-balanced InGaAs-InAlAs MQW grown on InP substrate using Molecular Beam Epitaxy. The InGaAs/InAlAs structures exhibit better absorption in the infrared spectrum, which is highly desirable because the cell can absorb lower energy light than GaAs/AlGaAs devices.