The new oxide paradigm for solid state ultraviolet photodetectors
The new oxide paradigm for solid state ultraviolet photodetectors
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固态紫外光电探测器的新氧化物范例
DOI：
10.1117/12.2319505
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发表时间：
2018
期刊：
影响因子：
--
通讯作者：
Teherani, Ferechteh H.
中科院分区：
文献类型：
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作者：
Sandana, Vinod E.;McClintock, Ryan;Razeghi, Manijeh;Harel, Shlomo;Arrateig, X.;Rogers, David J.;Bove, Philippe;Teherani, Ferechteh H.;Frisch, Eran;Teherani, Ferechteh H.
通过脉冲激光沉积在 2 英寸直径的 c-Al2O3 基底上生长的纤锌矿 ZnO 层的带隙通过与 Mg 合金化从 3.7 eV 调整到 4.8 eV。 高于此 Mg 含量，层从单相 hcp 转变为混合 hcp/fcc 相，然后变成高于约 5.5 eV 带隙的单相 fcc。 基于金叉指换能器结构的金属-半导体-金属 (MSM) 光电探测器是通过单步负光刻技术从单相 hcp 层制造出来的，然后封装在 TO5 罐中。 该器件在暗信号和光信号之间提供了超过 6 个数量级的分离，太阳抑制比 (I270: I350) 超过 3 × 105，暗信号为 300 pA（偏压为 -5V）。 光谱响应度经过精心设计，符合“Deutscher Verein des Gas- und Wasserfaches”行业标准形式，并且比商用 SiC 设备的响应度高出 20 多年（14 A/W，峰值为 270 nm）。 均质的 Ga2O3 层也通过 PLD 在 2 英寸直径的 c-Al2O3 基板上生长。 当薄膜厚度从 825 nm 减少到 145 nm 时，光学透射光谱与带隙从 4.9 eV 增加到 5.4 eV 一致。 X射线衍射表明薄膜为β-Ga2O3(单斜)多型体，具有强(-201)取向。 β-Ga2O3MSM 光电探测器的暗信号和光信号（-5V 偏压）之间的分离超过 4 个数量级，暗电流为 250 pA，光谱响应度高达 40 A/W（-0.75V 偏压）。 研究发现，通过将膜厚度从825 nm减小到145 nm，光谱响应度峰值位置可以从250 nm减小到230 nm。 峰值响应率波长随膜厚度的变化 (a) 与在相同层的透射光谱中观察到的表观带隙变化一致，并且 (b) 方便地提供了 MgZnO 层显示 fcc/hcp 相混合的光谱区域的覆盖范围。
The bandgap of wurzite ZnO layers grown on 2 inch diameter c-Al2O3substrates by pulsed laser deposition was engineered from 3.7 to 4.8 eV by alloying with Mg. Above this Mg content the layers transformed from single phase hcp to mixed hcp/fcc phase before becoming single phase fcc above a bandgap of about 5.5 eV. Metal-Semiconductor-Metal (MSM) photodetectors based on gold Inter-Digitated-Transducer structures were fabricated from the single phase hcp layers by single step negative photolithography and then packaged in TO5 cans. The devices gave over 6 orders of magnitude of separation between dark and light signal with solar rejection ratios (I270: I350) of over 3 × 105and dark signals of 300 pA (at a bias of -5V). Spectral responsivities were engineered to fit the “Deutscher Verein des Gas- und Wasserfaches” industry standard form and gave over two decade higher responsivities (14 A/W, peaked at 270 nm) than commercial SiC based devices. Homogeneous Ga2O3layers were also grown on 2 inch diameter c-Al2O3substrates by PLD. Optical transmission spectra were coherent with a bandgap that increased from 4.9 to 5.4 eV when film thickness was decreased from 825 to 145 nm. X-ray diffraction revealed that the films were of the β-Ga2O3(monoclinic) polytype with strong (-201) orientation. β-Ga2O3MSM photodetectors gave over 4 orders of magnitude of separation between dark and light signal (at -5V bias) with dark currents of 250 pA and spectral responsivities of up to 40 A/W (at -0.75V bias). It was found that the spectral responsivity peak position could be decreased from 250 to 230 nm by reducing film thickness from 825 to 145 nm. This shift in peak responsivity wavelength with film thickness (a) was coherent with the apparent bandgap shift that was observed in transmission spectroscopy for the same layers and (b) conveniently provides a coverage of the spectral region in which MgZnO layers show fcc/hcp phase mixing.