CuIn $_{1-x}$ Ga $_x$ Se $_{2}$中的本征点缺陷：混合密度泛函计算预测p型和n型导电性的起源
Native point defects in CuIn$_{1-x}$Ga$_x$Se$_{2}$: hybrid density functional calculations predict origin of p- and n-type conductivity
摘要：
基于HSE 06杂化泛函理论，我们对CuIn $_{1-x}$ Ga $_x$ Se $_{2}$中由于本征点缺陷引起的p型和n型导电性进行了第一性原理研究.能带排列表明，由于导带最小值的增加，$x$的带隙变大，使得难以在CuGaSe $_{2}$中建立n型导电性。由缺陷形成能可知，In/$_{\mathrm{Cu}}$是浅施主，$_{\mathrm{Cu}}$，VPDMATHABMR和Cu $_{\mathrm{In}/\mathrm{Ga}}$是浅受主.利用电离缺陷和本征载流子的总电荷中性来确定费米能级，我们表明，在富In生长条件下，在$_{\mathrm{Cu}}$导致强烈的n型导电性CuInSe $_{2}$。在贫In生长条件下，CuInSe $_{2}$中的导电类型改变为p型，并且In $_{\mathrm{Cu}}$对受主的补偿减少，如在光致发光实验中观察到的。在CuGaSe $_{2}$中，原生受主钉扎远离导带最小值的费米能级，从而抑制n型导电性。另一方面，CuGaSe $_{2}$在宽范围的贫Ga生长条件下显示出强的p型导电性。最大p型导电性CuIn $_{1-x}$ Ga $_x$ Se $_{2}$在In/Ga-贫生长条件下达到，与In/Ga-贫化学计量样品上的电荷浓度测量一致，并且主要是由于占主导地位的受主Cu $_{\mathrm{In}/\mathrm{Ga}}$。
英文摘要：
We have performed a first-principles study of the p- and n-type conductivity in CuIn$_{1-x}$Ga$_x$Se$_{2}$ due to native point defects, based on the HSE06 hybrid functional. Band alignment shows that the band gap becomes larger with $x$ due to the increasing conduction band minimum, rendering it hard to establish n-type conductivity in CuGaSe$_{2}$. From the defect formation energies, we find that In/Ga$_{\mathrm{Cu}}$ is a shallow donor, while V$_{\mathrm{Cu}}$, V$_{\mathrm{In}/\mathrm{Ga}}$ and Cu$_{\mathrm{In}/\mathrm{Ga}}$ act as shallow acceptors. Using total charge neutrality of ionized defects and intrinsic charge carriers to determine the Fermi level, we show that under In-rich growth conditions In$_{\mathrm{Cu}}$ causes strongly n-type conductivity in CuInSe$_{2}$. Under In-poor growth conditions the conductivity type in CuInSe$_{2}$ alters to p-type and compensation of the acceptors by In$_{\mathrm{Cu}}$ reduces, as observed in photoluminescence experiments. In CuGaSe$_{2}$, the native acceptors pin the Fermi level far away from the conduction band minimum, thus inhibiting n-type conductivity. On the other hand, CuGaSe$_{2}$ shows strong p-type conductivity under a wide range of Ga-poor growth conditions. Maximal p-type conductivity in CuIn$_{1-x}$Ga$_x$Se$_{2}$ is reached under In/Ga-poor growth conditions, in agreement with charge concentration measurements on samples with In/Ga-poor stoichiometry, and is primarily due to the dominant acceptor Cu$_{\mathrm{In}/\mathrm{Ga}}$.
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