ZnSnN(2), a new earth-abundant semiconductor, is synthesized and characterized for use as a photovoltaic absorber material. Results confirm the predicted orthorhombic Pna2(1) crystal structure in RF sputtered thin films. Additionally, optical measurements reveal a direct bandgap of about 2 eV, which is larger than our calculated bandgap of 1.42 eV due to the Burstein-Moss effect.

ZnSn1‐xGexN2 direct bandgap semiconductor alloys, with a crystal structure and electronic structure similar to InGaN, are earth‐abundant alternatives for efficient, high‐quality optoelectronic devices and solar‐energy conversion. The bandgap is tunable almost monotonically from 2 eV (ZnSnN2) to 3.1 eV (ZnGeN2) by control of the Sn/Ge ratio.

Light trapping is an important issue for thin film silicon photovoltaic cells due to the limited absorption coefficient for near infrared light. In this letter, we present a photonic structure that combines porous anodic aluminum oxide with a distributed Bragg reflector (DBR) on the backside of Si cells for light trapping. Simulation results show that this low-cost, self-assembled structure can provide more than 50% relative efficiency enhancement for a 2 m thin film crystalline Si solar cell, as compared to a reference cell without any back structure. As a proof of concept, we incorporated the backside structure into thick silicon wafers. The enhancement of light absorption near the band edge of silicon is demonstrated for our proposed light-trapping structure, in agreement with the theoretical predictions.

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