MgZnO/ZnO two-dimensional electron gas (2DEG) structures with ZnO annealed at various temperatures (600–900 °C) and photodetectors (PDs) with and without a 2DEG structure were fabricated using a radio frequency magnetron sputtering system. It was found that the carrier concentration and mobility increase with the annealing temperature owing to the improved crystalline in ZnO; however, high-temperature (800 °C or higher) annealing can degrade the crystalline of the ZnO layer. Hall measurements showed that compared with that of bulk ZnO, the sheet carrier concentration of the 2DEG sample increased from 1.3 × 10¹³ to 1.2 × 10¹⁴ cm^–2, and the mobility was enhanced from 5.1 to 17.5 cm²/V s. This is because the channel layer is the total thickness (300 nm) in bulk ZnO, whereas the carriers are confined to a 45 nm region beneath the MgZO layer in the 2DEG sample, confirming the 2DEG behavior at the MgZnO/ZnO interface. The PDs with 2DEG structures demonstrate a higher ultraviolet (UV) response and a UV/visible rejection ratio that is six times larger than that of the PDs without a 2DEG structure. The 2DEG structure also induces a photocurrent gain, which results in a 240% quantum efficiency for the 310 nm incident wavelength. The related mechanism is elucidated with a band diagram.

中文翻译：

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射频溅射制备的MgZnO / ZnO二维电子气光电探测器

使用射频磁控溅射系统制造了具有在不同温度（600–900°C）下退火的ZnO的MgZnO / ZnO二维电子气（2DEG）结构以及具有和不具有2DEG结构的光电探测器（PD）。研究发现，由于ZnO中结晶度的提高，载流子浓度和迁移率随退火温度的增加而增加。但是，高温（800°C或更高）退火会降低ZnO层的晶体。霍尔测量表明，与块状ZnO相比，2DEG样品的薄层载流子浓度从1.3×10 ¹³增加到1.2×10 ¹⁴ cm ^–2，迁移率从5.1增加到17.5 cm ²/秒 这是因为通道层是整体ZnO的总厚度（300 nm），而载流子被限制在2DEG样品中MgZO层下方的45 nm区域，从而确认了MgZnO / ZnO界面处的2DEG行为。具有2DEG结构的PD表现出更高的紫外线（UV）响应，其UV /可见光抑制比是没有2DEG结构的PD的六倍。2DEG结构还感应出光电流增益，从而在310 nm入射波长下产生240％的量子效率。用能带图阐明了相关的机制。