ABSTRACT

This chapter presents the experimental results achieved within only two growths using a well-researched metal organic vapour phase epitaxy-grown gallium arsenide/Aluminium Gallium Arsenide material system. It explores the advances made with a new device structure for photovoltaic solar cells. The chapter discusses a large bandgap material in the front and a gradual reduction of the bandgap towards the back of the solar cell, a major part of the solar spectrum can be absorbed while reducing thermalisation losses. The potential barrier height for electron flow through the device structure is determined by the large bandgap of the window material. The aim was to gradually convert the material layers from i-type to p-type electrical conductivity from the middle to the front of the device, forming an overall graded bandgap p-i-n type device structure. The multi-layer graded bandgap device structure also utilises a major part of infrared radiation, minimising transmission losses.