Direct observation of an atomic thin inversion layer at the native oxide/ n-Si interface

A recombination-free high-quality interface is desired for all semiconductor solar cells. An induced inversion layer and the resulting concentrated surface electric field are critical factors for the reduction of photocarrier recombination. The surface inversion layer has been widely predicted at the interface of two materials with different work functions leading to large energy band bending. Herein, we present the direct observation of an atomic thin hole inversion layer between cubic-phase indium tin oxide (c-ITO)/native oxide/n-Si interface using transmission electron microscopy. Excellent lattice matching, atomic oxidation of pristine Si substrate and interfacial charge engineering enable this high-quality interface and its revelation. A facile process of air-annealing and commensurate adjacent thin film phase transition is explored. The device exhibits an ultra-low recombination rate at the interface and internal quantum efficiency (IQE) of over 97% for a broad range of wavelengths. This presentation will provide an understanding of the silicon - native oxide semiconductor interface as developed via facile processing and electron microscopy.