Plasmon-mediated hot carrier injection using the metal–semiconductor Schottky diode structure has been proposed for optical sensing and solar energy harvesting. But the low conversion efficiency and limited spectral range are the current concerns. Wide-bandgap (3.4 eV) gallium nitride (GaN) has been considered as an excellent semiconductor material for broadband conversion of photonic energy, but the achievable efficiency is still rather low. Here, we demonstrate an efficient hot-hole injection mechanism based on the photoconductive titanium nitride (TiN)/p-type GaN (p-GaN) metal–semiconductor heterostructure grown by molecular-beam epitaxy. Compared with the same device structure using a TiN/n-GaN heterojunction, the photocurrent conversion efficiency is increased 4 orders of magnitude. Moreover, an internal photovoltage, generated by interfacial charge transfer/separation across the TiN/p-GaN Schottky barrier (1.2 eV), enables a self-sustainable photocurrent without external biasing. For practical applications, the refractory material properties and broadband conversion (365–1033 nm) make this heterostructure system capable of harvesting highly concentrated solar light.

中文翻译：

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用于高效光子能量收集的外延 TiN/GaN 异质结构

已经提出使用金属-半导体肖特基二极管结构的等离子体介导的热载流子注入用于光学传感和太阳能收集。但低转换效率和有限的光谱范围是当前关注的问题。宽带隙 (3.4 eV) 氮化镓 (GaN) 已被认为是用于光子能量宽带转换的优秀半导体材料，但可实现的效率仍然相当低。在这里，我们展示了一种基于通过分子束外延生长的光电导氮化钛 (TiN)/p 型 GaN (p-GaN) 金属-半导体异质结构的有效热空穴注入机制。与使用TiN/n-GaN异质结的相同器件结构相比，光电流转换效率提高了4个数量级。此外，内部光电压，通过跨 TiN/p-GaN 肖特基势垒 (1.2 eV) 的界面电荷转移/分离产生，可实现无需外部偏置的自持光电流。对于实际应用，耐火材料特性和宽带转换（365-1033 nm）使这种异质结构系统能够收集高度集中的太阳光。