Capacitance behavior of InAlN Schottky diodes in presence of large concentrations of shallow and deep states related to oxygen
Capacitance behavior of InAlN Schottky diodes in presence of large concentrations of shallow and deep states related to oxygen
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DOI：
10.1063/1.4919846
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发表时间：
2015-05-14
影响因子：
3.2
通讯作者：
Grandjean, N.
中科院分区：
文献类型：
--
作者：
Py, M. A.;Lugani, L.;Grandjean, N.
测量了非故意掺杂的In0.16Al0.84N/n(+)-GaN肖特基二极管在1 MHz和90-400K范围内的电容-电压-温度特性。它们是在现有理论的框架下讨论的，这些理论适当地处理了泊松方程，特别是在空间电荷区边缘附近，即所谓的过渡区。以前报道的浅施主和深DX类中心的浓度被适当地确定。讨论电容的温度依赖关系的关键参数是小交流调制信号的频率与每个电平的随温度变化的发射率之间的比率。在整个温度范围内，用三参数表达式成功地拟合出了电容-电压C-V-a曲线。浅能级和深能级的浓度都超过了10(18)cm(-3)。基于二次离子质谱图，我们将这两个能级都指定为主要的氧杂质。这一结果支持了我们之前将浅施主指定为氮位置上的替代氧原子，将深态指定为与O相关的DX中心，自然地解释了它的高浓度。在270K以下的C-V-a曲线上出现了滞后的C-V-a曲线。此外，在150K以下，当浅施主和深施主由于发射频率低于1 MHz调制频率而不再响应时，低温下的迟滞动力学与位于过渡区附近的大量深能级有关。最后，正如在其他III-氮化物中已经报道的那样，高度掺杂的薄表面势垒的存在得到了进一步的支持。(C)2015 AIP出版有限责任公司。
The capacitance-voltage-temperature characteristics of nonintentionally doped In0.16Al0.84N/n(+)-GaN Schottky diodes were measured at 1MHz and in the 90-400K range. They are discussed in the framework of existing theories, which properly treat the Poisson's equation, especially near the edge of the space-charge region, the so-called transition region. The concentration of a shallow donor and of a deep DX-like center, previously reported, is properly determined. The key parameter to discuss the temperature dependence of the capacitance is the ratio between the frequency of the small ac modulating signal and the temperature-dependent emission rate associated to each level. The capacitance-voltage C-V-a curves were successfully fitted using a three parameters expression over the full range of temperatures. The concentration of both shallow and deep levels exceeds a few 10(18) cm(-3). Based on secondary ion mass spectrometry profiling, we assign both levels to the dominant oxygen impurity. This result supports our previous assignment of the shallow donor to a substitutional oxygen atom on a nitrogen site and the deep state to an O-related DX center, naturally explaining its high concentration. The sluggish kinetics at low temperatures, associated to the large concentration of deep levels located near the transition region, is illustrated by hysteresis loops in the C-V-a curves below 270 K. Furthermore, the contribution of free carriers to the capacitance is revealed below 150 K, when both shallow and deep donors cannot respond anymore due to an emission rate lower than the 1MHz modulating frequency. Finally, the presence of a highly doped thin surface barrier, as already reported in other III-nitrides, finds further support. (c) 2015 AIP Publishing LLC.