Chemical treatment effects on Schottky contacts to metalorganic chemical vapor deposited n-type N-polar GaN
Chemical treatment effects on Schottky contacts to metalorganic chemical vapor deposited n-type N-polar GaN
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DOI：
10.1063/5.0015140
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发表时间：
2020-08
影响因子：
3.2
通讯作者：
D. Khachariya;D. Szymanski;R. Sengupta;P. Reddy;E. Kohn;Z. Sitar;R. Collazo;S. Pavlidis
中科院分区：
文献类型：
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作者：
D. Khachariya;D. Szymanski;R. Sengupta;P. Reddy;E. Kohn;Z. Sitar;R. Collazo;S. Pavlidis
在这项工作中，我们研究了不同的化学处理，如溶剂，碱和酸，对在金属有机化学气相沉积生长的n型N-极性GaN上制备的肖特基二极管的表面性质和电学行为的影响。结果表明，生长的肖特基二极管的I-V势垒高度为0.40 eV，C-V势垒高度为0.60 eV，理想因子n=1.07。研究发现，溶剂处理并没有像预期的那样改变肖特基二极管的表面和电性能。然而，碱性光刻显影剂和酸的处理降低了N极GaN的性能，后者通常用于在金属接触沉积之前清洁GaN薄膜的表面。这些碱和酸处理会产生三角形/六角形的晶面，从而使表面严重粗糙。这些经过碱处理和酸处理的二极管的I-V势垒高度和C-V势垒高度分别增加到0.63 eV和1.00 eV，理想因子值为1.2。X射线光电子能谱研究表明，与原始样品表面相比，碱处理和酸处理表面的氧含量较低。可以理解，碱和酸处理的二极管势垒高度的增加可能是由于这些结晶学特征上的极性变化，从N-极到半极/非极。所有这些结果表明，与Ga极GaN不同，N极GaN表面对碱和酸具有很高的反应性。
In this work, we investigate the effect of different chemical treatments, such as solvents, bases, and acids, on the surface properties and electrical behavior of Schottky diodes fabricated on metalorganic chemical vapor deposition-grown, n-type, N-polar GaN. The I–V and C–V barrier heights of the as-grown Schottky diodes are found to be 0.40 eV and 0.60 eV, respectively, with an ideality factor n = 1.07. It is found that the solvent treatments neither change the surface nor the electrical performance of the Schottky diodes, as expected. However, the treatments by the alkaline photolithography developer and acid—the latter of which is often used to clean the surface of Ga-polar GaN films prior to metal contact deposition—degrade the performance of N-polar GaN. These base and acid treatments severely roughen the surface by creating triangular/hexagonal crystallographic facets. The I–V and C–V barrier heights of these base- and acid-treated diodes are increased to 0.63 eV and 1.00 eV, respectively, with ideality factor values n < 1.2. X-ray photoelectron spectroscopy studies indicate that base- and acid-treated surfaces have lower oxygen content as compared to the as-grown sample surface. It is understood that the increment in the barrier height for base- and acid-treated diodes could be due to the change in polarity, from N-polar to semi-polar/non-polar, on these crystallographic features. All these results demonstrate that, unlike for Ga-polar GaN, the N-polar GaN surface is highly reactive to bases and acids.