Shallow donor and deep DX-like center in InAlN layers nearly lattice-matched to GaN
Shallow donor and deep DX-like center in InAlN layers nearly lattice-matched to GaN
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DOI：
10.1103/physrevb.90.115208
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发表时间：
2014-09
影响因子：
3.7
通讯作者：
M. Py;L. Lugani;Y. Taniyasu;J. Carlin;N. Grandjean
中科院分区：
文献类型：
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作者：
M. Py;L. Lugani;Y. Taniyasu;J. Carlin;N. Grandjean
用金属-有机气相外延方法生长了200 nm厚的非故意掺杂In0.16Al0.84N/n(+)-GaN样品，并用于InAlN的电学表征。在180-400K温度范围内，肖特基二极管的正向电流在1.2V以下以隧道机制为主。在90-400K温度范围内，在1 MHz频率下测量了不同电压下的电容和电导-温度特性。电导随温度的变化曲线显示两个峰D-1和D-2，这两个峰属于InAlN中的体态。导纳光谱表征得到它们的热激活能分别约为68 meV和290 meV，热俘获截面分别为9.7×10(-17)cm(2)和6.2×10(-15)cm(2)。从肖特基二极管的I-V-T特性中提取InAlN中性区的载流子浓度与温度的关系也揭示了相同的能级。在已有的DX中心理论的框架下，证明并讨论了部分载流子冻结。这种方法的使用得到了持续光导效应的证据的支持，这有力地表明了我们材料中DX中心的存在。结果表明，InAlN中的每个施主都以两种不同的晶格构型存在，一种是替代晶格构型(D-1，氢化态)，另一种是晶格扭曲构型(D-2，Dx态)。根据二次离子质谱仪数据、理论依据和之前在AlxGa1-xN系统中的实验证据，氧是这种无意掺杂剂最有可能的候选者。
Nonintentionally doped 200-nm-thick In0.16Al0.84N/n(+)-GaN samples were grown by metal-organic vapor phase epitaxy and used for the electrical characterization of InAlN. In the temperature range 180-400 K, the forward current of Schottky diodes is dominated by a tunneling mechanism below 1.2 V. Capacitance and conductance-temperature characteristics were measured at 1 MHz in the 90-400 K range and at various voltages. The conductance vs temperature reveals two peaks D-1 and D-2, which are attributed to bulk states in InAlN. Their characterization by admittance spectroscopy gives thermal activation energies of approximate to 68 meV and 290 meV, and thermal capture cross section of 9.7 x 10(-17) cm(2) and approximate to 6.2 x 10(-15) cm(2), respectively. The same levels are also revealed by extracting the temperature dependence of the carrier density in the neutral region of InAlN from I-V-T characteristics on the Schottky diode. A partial carrier freeze out is demonstrated and discussed in the framework of an existing theory for DX centers. The use of this approach is supported by the evidence of persistent photoconductivity effects, which strongly indicate the presence of DX centers in our material. It results that each donor in InAlN would exist in two distinct lattice configurations, a substitutional one (D-1, hydrogenic state) and a lattice-distorted one (D-2, DX state). From secondary ion mass spectrometry data, theoretical grounds, and previous experimental evidence in the AlxGa1-xN system, oxygen is the most probable candidate for such an unintentional dopant.