Enhanced p-Type Doping in Polycrystalline CdTe Films: Deposition and Activation
Enhanced p-Type Doping in Polycrystalline CdTe Films: Deposition and Activation
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多晶 CdTe 薄膜中增强的 p 型掺杂：沉积和激活
DOI：
10.1109/jphotov.2019.2902356
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发表时间：
2019
影响因子：
3
通讯作者：
W. Metzger
中科院分区：
文献类型：
--
作者：
B. McCandless;W. Buchanan;Gowri Sriramagiri;C. Thompson;J. Duenow;D. Albin;S. Jensen;J. Moseley;M. Al‐Jassim;W. Metzger
提出了一种利用 Te 上的 V 族取代将多晶 CdTe 薄膜中的空穴密度提高到 10<sup>16</sup> cm<sup>-3</sup> 的<italic>原位</italic>非平衡方法。掺杂 P、As 和 Sb 的单相 CdTe 薄膜在 550°C 下以 100–200 nm/s 的速度沉积到移动的硫化镉/高电阻透明缓冲层/透明导电氧化物/玻璃覆盖层上，通过高纯度化合物源在 Cd 超压下进行气相传输沉积。通过诊断装置的电容电压分析确定激活前后的掺杂水平。二次离子质谱深度分析证实沉积薄膜中的掺杂剂掺入水平为 10<sup>17</sup>–10<sup>18</sup> 原子/cm<sup>3</sup>。通过在 Cd 或 CdCl<sub>2</sub> 蒸气中进行沉积后退火并快速冷却来进行电子激活，与中间的 -10<sup>14</sup> 相比，P 的受主浓度增加至 >10<sup>15</sup> cm<sup>-3</sup>，As 和 Sb 的受主浓度增加至 >10<sup>16</sup> cm<sup>-3</sup>未掺杂 CdTe 薄膜的 cm<sup>−3</sup> 受体能级。该激活方法与目前用于高效 CdTe 太阳能电池的沉积后处理兼容。对于掺杂剂As和Sb，受主浓度分别通过取代As<sub>Te</sub>和Sb<sub>Te</sub>的形成而增加，这通过阴极发光光谱得到了验证。
An <italic>in situ</italic> nonequilibrium method to increase hole density in polycrystalline CdTe thin films to 10<sup>16</sup> cm<sup>−3</sup> using group V substitution on Te is presented. Single-phase CdTe films doped with P, As, and Sb were deposited at 550 °C at 100–200 nm/s onto moving cadmium sulfide/high resistance transparent buffer layer/transparent conductive oxide /glass superstrates by vapor transport deposition in Cd overpressure from high purity compound sources. Doping levels before and after activation were determined by capacitance-voltage analysis of diagnostic devices. Secondary ion mass spectrometry depth profiling confirmed dopant incorporation levels of 10<sup>17</sup>–10<sup>18</sup> atoms/cm<sup>3</sup> in as-deposited films. Electronic activation was carried out by post-deposition annealing in Cd or CdCl<sub>2</sub> vapor with fast cooling, increasing acceptor concentrations to >10<sup>15</sup> cm<sup>−3</sup> for P and >10<sup>16</sup> cm<sup>−3</sup> for As and Sb, compared with mid −10<sup>14</sup> cm<sup>−3</sup> acceptor levels for undoped CdTe films. The activation methods are compatible with post-deposition processing presently used for high-efficiency CdTe solar cells. For the dopants As and Sb, the acceptor concentration increased by substitutional As<sub>Te</sub> and Sb<sub>Te</sub> formation, respectively, which was validated by cathodoluminescence spectroscopy.