Advances and perspectives in the growth of III-N heterostructures for solar cells: an overview

Abstract

This review discusses recent advancements in the fabrication of III-N based solar cells, emphasizing the technical challenges that have impeded efforts to enhance their efficiency. It also assesses the current status and future potential of growing heterostructures for these solar cells using various methods. III-N are characterized by a high solar light absorption coefficient and excellent radiation resistance, which give them a distinct advantage over silicon and gallium arsenide. These properties make. III-N particularly suitable for manufacturing space-grade solar cells. However, most experimentally fabricated III-N based solar cells exhibit lower efficiencies than those predicted theoretically. This review identifies the main limitations in the growth of III-N based solar cells, including spinodal decomposition, spontaneous and piezoelectric polarization effects, difficulties in achieving p-type conductivity, high density of dislocations (greater than 106 cm−2), narrow indium concentration ranges for thermodynamically stable compositions, challenges in growth thick layers with high indium content, and the absence of a native substrate for III-N materials. The review compares and thoroughly analyzes the advantages and disadvantages of each method used to fabricate III-N based solar cells, ultimately recommending metalorganic chemical vapor deposition (MOCVD) as the optimal growth technique. For MOCVD, it is suggested that substrate temperature are set between 700 and 800 °C for InGaN layers and 1000–1100 °C for AlGaN and AlInN layers. This review not only summarizes the latest achievements in the development of III-N materials for space solar cells, but also highlights the main problems of their manufacture and describes the directions of future research in this area.