npsm 새물리 New Physics : Sae Mulli

pISSN 0374-4914 eISSN 2289-0041


Research Paper

New Phys.: Sae Mulli 2018; 68: 381-386

Published online April 30, 2018

Copyright © New Physics: Sae Mulli.

Internal Electric Field Caused by the Doping Concentration in the Emitter Layer in p$^+$-n-n$^+$ GaAs Solar Cells

Mo Geun SO1, Hyun-Jun JO1, Young Hee MUN1, Jong Su KIM*1, Yeongho KIM2, Jun Oh KIM2, Sang Jun LEE2

1 Department of Physics, Yeungnam University, Gyeongsan 38541, Korea
2 Korea Research Institute of Standards and Science, Daejeon 34113, Korea


Received: November 23, 2017; Revised: February 12, 2018; Accepted: March 2, 2018

This is an open-access article distributed under the terms of the Creative Commons Attribution Non-Commercial License ( which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

The internal electric field ($F$) of GaAs solar cells (SC) with different doping concentrations of the emitter layers has been investigated by using photoreflectance (PR) spectroscopy. At room temperature, the $F$ of the highly doped SC (HDSC) is 91.5 kV/cm, which is lower than the 6.3 kV/cm for the low-doping SC (LDSC). From the excitation-light-intensity ($I_{ex}$)-dependent PR, the drop in $F$ is about 20 kV/cm, which is larger than the theoretical value. The large drop in $F$ in the HDSC is confirmed to have been caused by an enhancement of the field screening effect resulting from the higher potential barrier effect of the window layer. Also, in the case of the LDSC, the rapid decrease in $F$ with decreasing temperature can be explained by a change in the height of the potential barrier.

Keywords: GaAs, Solar cell, Doping concentration, Internal electric field

본 연구에서는 GaAs 태양전지의 에미터층의 도핑 농도에 따른 내부 전기장($F$)의 변화를 반사변조분광법(photoreflectance, PR)으로 조사하였다. 상온에서 관측된 $F$의 세기는 도핑농도가 높은 태양전지(high doping solar cell, HDSC)에서 91.5 kV/cm로 도핑농도가 낮은 태양전지(low doping solar cell, LDSC)보다 6.3 kV/cm 낮았다. 여기광세기에 따른 PR 실험결과 $F$의 변화폭은 약 20 kV/cm로서 이론적인 값보다 크게 관측되었다. 이는 도핑농도가 높은 경우 윈도층의 전위장벽이 상대적으로 높아져서 전기장 가림 효과가 증가하였기 때문으로 판단되었다. 또한 도핑농도가 낮은 경우, 시료의 온도가 낮아질수록 $F$가 더 빠르게 감소하는 것은 도핑농도의 변화에 의한 전위장벽 높이의 변화 때문으로 설명하였다.

Keywords: GaAs, 태양전지, 도핑농도, 내부 전기장

Fig. 1. PR spectra of LDSC and HDSC at Room temperature. The inset is the fast Fourier transform results for FKOs of LDSC and HDSC.

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