MOVPE issues in the development of ordered GaInP metamorphic buffers for multijunction solar cells

Abstract

Metamorphic solar cells require high-quality compositional graded buffer (CGB) layers to perform as virtual substrate. Several technical growth issues arisen during the implementation of an ordered-GaInP CGB at IES-UPM MOVPE reactor are discussed in this work. These considerations focuses on achieving high-quality metamorphic buffers by increasing phosphine partial pressure and growth rates, which requires some reactor adjustments, and attaining composition control for different GaInP alloys. Improvements on the material quality are proved. It is also presented a 1 eV GaInAs metamorphic subcell and an inverted metamorphic triple junction solar cell using these CGB.