SnO/β-Ga2O3 vertical pn heterojunction diodes
SnO/β-Ga2O3 vertical pn heterojunction diodes
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DOI：
10.1063/5.0031442
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发表时间：
2020-12-21
影响因子：
4
通讯作者：
Bierwagen, Oliver
中科院分区：
文献类型：
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作者：
Budde, Melanie;Splith, Daniel;Bierwagen, Oliver
作为对（透明）双极氧化物电子学的贡献，通过等离子体辅助分子束外延法在电子浓度为n = 2.0 x1017 cm(-3)的无意掺杂的n型β-Ga2O3(-201)基板上制备了空穴浓度范围为p = 1018至10(19)cm(-3)的无意掺杂的p型SnO层，制备了垂直pn异质结二极管。 SnO 层由 (001) 取向晶粒组成，与衬底没有面内外延关系。在随后的接触处理和台面蚀刻（这大大减少了 SnO 层中的反向电流扩散和相关的高泄漏）之后，通过电流-电压和电容-电压测量进行电气表征。结果揭示了正向偏压下热电子发射的 I 型能带排列和结传输。确定了 +/- 1V 下的 2 x10 8 整流、1.16 的理想因子、3.9 mΩ cm(2) 的微分特定导通电阻以及 0.96V 的内置电压。在对顶部 SnO 层进行范德堡霍尔测量期间，pn 结隔离可防止高导电性 Ga2O3 衬底中的并联传导，这凸显了将横向传输器件中的 p 型功能与底层 n 型衬底的功能去耦的潜力。测得的二极管最大反向击穿电压为 66V，对应于 Ga2O3 耗尽区中 2.2MV/cm 的峰值击穿电场，表明 SnO 的低带隙（大约 0.7 eV）不是击穿的限制因素。高压器件所需的更高击穿电压可以通过降低界面处的 β-Ga2O3 中的施主浓度来增加耗尽宽度，以及改善接触几何形状以减少场拥挤来实现。
As a contribution to (transparent) bipolar oxide electronics, vertical pn heterojunction diodes were prepared by plasma-assisted molecular beam epitaxy of unintentionally doped p-type SnO layers with hole concentrations ranging fromp =1018 to 10(19)cm(-3) on unintentionally doped n-type beta -Ga2O3(-201) substrates with an electron concentration ofn = 2.0 x1017 cm(-3). The SnO layers consist of (001)-oriented grains without in-plane epitaxial relation to the substrate. After subsequent contact processing and mesa-etching (which drastically reduced the reverse current spreading in the SnO layer and associated high leakage), electrical characterization by current-voltage and capacitance-voltage measurement was performed. The results reveal a type-I band alignment and junction transport by thermionic emission in forward bias. A rectification of2 x10 8 at +/- 1V, an ideality factor of 1.16, a differential specific on-resistance of 3.9 mOmega cm(2), and a built-in voltage of 0.96V were determined. The pn-junction isolation prevented parallel conduction in the highly conductive Ga2O3 substrate during van-der-Pauw Hall measurements of the SnO layer on top, highlighting the potential for decoupling the p-type functionality in lateral transport devices from that of the underlying n-type substrate. The measured maximum reverse breakdown voltage of the diodes of 66V corresponds to a peak breakdown field of 2.2MV/cm in the Ga2O3-depletion region and suggests the low bandgap of the SnO (approximate to 0.7 eV) not to be the limiting factor for breakdown. Higher breakdown voltages that are required in high-voltage devices could be achieved by reducing the donor concentration in the beta -Ga2O3 toward the interface to increase the depletion width, as well as improving the contact geometry to reduce field crowding.