Revealing the TMA 2 SnI 4 /GaN band alignment and carrier transfer across the interface

• Published in: Journal of materials chemistry. C, Materials for optical and electronic devices
• Main Authors: Zdanowicz, Ewelina, Przypis, Łukasz, Żuraw, Wiktor, Grodzicki, Miłosz, Chlipała, Mikołaj, Skierbiszewski, Czesław, Herman, Artur P., Kudrawiec, Robert
• Format: Journal Article
• Language: English
• Published: 2024
• ISSN: 2050-7526; 2050-7534
• DOI: 10.1039/D4TC03203A

In this study, we investigate the electronic properties of the GaN junction with TMA 2 SnI 4 – (2-thiophene)methylammonium tin iodide, a Pb-free 2D perovskite. Through spectroscopic analysis, we explore the impact of TMA 2 SnI 4 on surface Fermi level pinning on Ga-polar GaN surfaces, revealing insights into carrier transfer at the interface. Our findings demonstrate that TMA 2 SnI 4 induces an upward shift in the surface Fermi level of GaN, resulting in a reduction in the surface barrier for electrons and an increase for holes. This indicates electron transfer from TMA 2 SnI 4 to GaN and hole transfer in the opposite direction. Furthermore, utilizing ultraviolet photoelectron spectroscopy, we determine the positions of the conduction and valence bands in TMA 2 SnI 4 relative to the vacuum level to be −3.05 eV and −5.2 eV, respectively. Based on these findings, we identify a type II band alignment at the TMA 2 SnI 4 /GaN interface, with band offsets of 0.2 eV and 1.5 eV for the conduction and valence bands, respectively. These electronic properties make the TMA 2 SnI 4 /GaN junction a promising candidate for active regions in optoelectronic devices, such as photodetectors and photonic synapses.