Development of thin film metamorphic GaSb cells by epitaxial lift-off from GaAs substrates

A flexible, lightweight GaSb solar cell has been attempted. The thin-film cell was bonded to a flexible carrier and isolated from the GaAs substrate by using epitaxial lift-off technique. The characteristics of the thin-film metamorphic GaSb cells are compared to regular metamorphic cells and lattice matched GaSb substrate cells. J-V characterization under 1 sun illumination is presented.

I. Introduction

GaSb solar cells are fabricated by Zn diffusion into n-GaSb substrates. Zn diffusion is a well-established inexpensive technique that has made GaSb cells widely available in the market [1]–[2]. However, recently there has been an increased interest in making GaSb cells by epitaxial techniques such as MOCVD or MBE [3]–[4]. These techniques allow for a number of variations to the structure of the cell that can potentially result in a more efficient cell such as the addition of window and back-surface reflector layers, the control of the base and emitter layer thickness and the change in polarity [4]–[6]. There is also the added possibility to grow monolithic multi-junction cells. Unfortunately, epitaxial growth is an expensive technique.