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Carrier dynamics and recombination in silicon doped InAs/GaAs quantum dot solar cells with AlAs cap layers
Semiconductor Science and Technology ( IF 1.9 ) Pub Date : 2020-09-30 , DOI: 10.1088/1361-6641/abb1c7
S Kondratenko 1, 2 , O Kozak 2 , S Rozouvan 2 , Yu I Mazur 3 , Y Maidaniuk 3 , J Wu 1, 4 , S Wu 1 , Zh M Wang 1 , S Chan 4 , D Kim 4 , H Liu 4 , G J Salamo 3
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The effects of doping InAs quantum dots (QDs) with Si on charge carrier dynamics and recombination in the InAs/GaAs quantum dot solar cells with AlAs cap layers was investigated. Non-radiative and radiative recombination paths in the doped cells were identified by changes in emission intensity, longwavelength photovoltage (PV) as well as time-resolved PV and photoluminescence (PL) measurements. We find that the reduction of long-wavelength PV and PL with n-doping is due to the electron population of the QD ground states and shrinkage of the depletion layer. The time constants, derived from the timeresolved PV, grow non-monotonically with increasing of the doping density in the QDs due to redistribution of electrostatic potential in the intrinsic region of p-i-n diode and electron population of EL2 defect states of GaAs barriers. We also find that the ground state emission from the InAs QDs decreases with n-doping. The results show that PL traces depends on carrier dynamic in the top QD layers populated partially with electrons from ionized impurities, whereas PV transients were found to be strongly dependent on recombination via QD and defect states located outside the depletion layer. We conclude that the non-radiative recombination of photogenerated electrons and holes via defects is suppressed due to the spatial separation by the local electric fields in and around doped AlAs/InAs QDs, as the potential profile of the intrinsic region is modulated spatially by built-in charges. The interpretation of experimental data suggests limiting mechanisms in the InAs/GaAs quantum dot solar cells operation and sheds light on possible approaches for their further improvement.

中文翻译:

具有 AlAs 帽层的硅掺杂 InAs/GaAs 量子点太阳能电池中的载流子动力学和复合

研究了用 Si 掺杂 InAs 量子点 (QD) 对具有 AlAs 帽层的 InAs/GaAs 量子点太阳能电池中电荷载流子动力学和复合的影响。通过发射强度、长波长光电压 (PV) 以及时间分辨 PV 和光致发光 (PL) 测量的变化来确定掺杂电池中的非辐射和辐射复合路径。我们发现 n 掺杂导致长波长 PV 和 PL 的减少是由于 QD 基态的电子数量和耗尽层的收缩。由于 pin 二极管本征区中静电势的重新分布和 GaAs 势垒的 EL2 缺陷态的电子数量,时间常数源自时间分辨 PV,随着 QD 中掺杂密度的增加而非单调增长。我们还发现 InAs QD 的基态发射随着 n 掺杂而降低。结果表明,PL 迹线取决于顶部 QD 层中的载流子动力学,其中部分填充有来自电离杂质的电子,而 PV 瞬变被发现强烈依赖于通过 QD 和位于耗尽层外的缺陷态的复合。我们得出的结论是,由于掺杂 AlAs/InAs QD 中和周围的局部电场的空间分离,光生电子和空穴通过缺陷的非辐射复合受到抑制,因为本征区的电势分布通过内置的空间调制在收费中。实验数据的解释表明 InAs/GaAs 量子点太阳能电池操作中的限制机制,并阐明了进一步改进它们的可能方法。
更新日期:2020-09-30
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