Comprehensive characterization of metal-semiconductor-metal ultraviolet photodetectors fabricated on single-crystal GaN
Comprehensive characterization of metal-semiconductor-metal ultraviolet photodetectors fabricated on single-crystal GaN
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DOI：
10.1063/1.367484
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发表时间：
1998-06-01
影响因子：
3.2
通讯作者：
Campbell, JC
中科院分区：
文献类型：
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作者：
Carrano, JC;Li, T;Campbell, JC
我们报告的材料，电气和光学性能的金属-半导体-金属紫外光探测器上制作的单晶GaN，有源层的1.5和4.0 μ m的厚度。我们已经模拟了电流传输在1.5 μ m的设备，使用电子场发射理论，并在4.0 μ m的设备，使用电子场发射理论。我们得到了一个很好的拟合实验数据。在1.5 μ m器件的重复场应力下，存在与陷阱相关的电流-电压（I-V）特性的劣化。我们假设GaN中的陷阱与表面缺陷（可能是螺纹位错）和深层次体状态的结合有关，这些状态在界面的隧穿距离内。一个简单的定性模型的基础上，实验结果。对于在具有非常低的背景自由电子浓度的晶片上制造的器件，存在特征“穿通”电压。这归因于耗尽区与下面的低温缓冲层的相互作用。我们还报告了在没有内部增益的情况下具有高量子效率（类似于50%）的GaN金属-半导体-金属光电探测器。这些光电探测器在带隙以上具有平坦的响应度（在类似于0.15 A/W下测量），在带边缘具有尖锐的可见盲截止。对于低于带隙能量的光子，没有可辨别的响应度。在-10 V反向偏压下，我们还获得了类似于800 fA的创纪录低暗电流。暗电流和紫外光响应I-V曲线在V-R>-25 V时非常平坦，并且没有显示出陷阱相关退化或穿通效应的证据。(C)1998年美国物理学会。[S0021-8979（98）05611-4]
We report on the material, electrical, and optical properties of metal-semiconductor-metal ultraviolet photodetectors fabricated on single-crystal GaN, with active layers of 1.5 and 4.0 mu m thickness. We have modeled current transport in the 1.5 mu m devices using thermionic field emission theory, and in the 4.0 mu m devices using thermionic emission theory. We have obtained a good fit to the experimental data. Upon repeated field stressing of the 1.5 mu um devices, there is a degradation in the current-voltage (I-V) characteristics that is trap related. We hypothesize that traps in the GaN are related to a combination of surface defects (possibly threading dislocations), and deep-level bulk states that are within a tunneling distance of the interface. A simple qualitative model is presented based on experimental results. For devices fabricated on wafers with very low background free electron concentrations, there is a characteristic "punch-through" voltage. which we attribute to the interaction of the depletion region with the underlying low-temperature buffer layer. We also report GaN metal-semiconductor-metal photodetectors with high quantum efficiencies (similar to 50%) in the absence of internal gain. These photodetectors have a flat responsivity above the band gap (measured at similar to 0.15 A/W) with a sharp, visible-blind cutoff at the band edge. There is no discernible responsivity for photons below the band-gap energy. We also obtained record low dark current of similar to 800 fA at -10 V reverse bias. The dark current and ultraviolet photoresponse I-V curves are very flat out to V-R>-25 V, and do not show evidence of trap-related degradation, or punch-through effects. (C) 1998 American Institute of Physics. [S0021-8979(98)05611-4]