This article was submitted to Optics and Photonics, a section of the journal Frontiers in Physics
This is an open-access article distributed under the terms of the
The electrical and spectral properties of 150 KeV proton-irradiated MBE-grown In0.53Ga0.47As single junction solar cell and its post-thermal annealing properties were investigated. Both simulation and experimental methods were applied to analyze the irradiation-induced displacement damage and degradation mechanism of cell performance. The results show that most protons would penetrate through the In0.53Ga0.47As emitter and stop in the base region, causing differing extents of electric and spectral degredation. When proton fluence were 1 × 1012 and 5 × 1012 p/cm2, the remaining factor of Isc, Voc, Pmax, and FF were degraded to 0.790, 0.767, 0.558, 0.921 and 0.697, 0.500, 0.285, 0.817, respectively. Severer degradation was found in short wave lengths compared to long wave lengths of the solar cell spectral response. After annealing treatments, the normalized Isc, Voc, Pmax, and FF, significantly recovered from 0.697, 0.500, 0.285, and 0.817 to 0.782, 0.700, 0.499, and 0.912 (fluence: 5 × 1012 p/cm2), and the irradiation-induced defects in the whole emission area and part of the base area were annihilated, so the observed recovery of the short wavelength of the solar cell was greater than the long wavelength. The performance analysis in this work provided valuable ways to improve the photoelectric efficiency of space solar cells.
Ⅲ-Ⅴ-based multi-junction solar cells as a direct energy provider are currently used for different space applications; radiation resistance of the solar cell will directly determine the service life of spacecraft and satellites. In order to accomplish extremely tough and long-term space missions, it is important to develop space solar cells with excellent radiation resistance and high conversion efficiency and stability. Over the past ten years, lattice-matched GaInP/GaAs/Ge three-junction solar cells with relatively high efficiency (
There are already many studies about the electrical properties of both InGaAs-based single and multi-junction solar cells. However, the radiation effects for InGaAs sub-cell of GaInP/GaAs//InGaAsP/InGaAs full spectra four-junction solar cells are still limited. Dai et al. [
Many scholars investigated the effects of proton irradiation with varying energy levels on Ⅲ-Ⅴ multi-junction solar cells, and concluded that the degradation caused by low-energy protons is more serious than high-energy protons [
In0.53Ga0.47As single junction solar cell was investigated in this work and its detailed structure is shown in
Structure representative of
In order to understand proton irradiation-induced displacement damage distribution in In0.53Ga0.47As sub-cells, the SRIM (Stopping and Range of ions in Matter) program was utilized to simulate the trajectories of 105 incident protons.
150 KeV proton with different fluence-irradiated In0.53Ga0.47As solar cells'
Extracted parameters of In0.53Ga0.47As solar cells from I-V curves.
Fluence (p/cm2) | Isc (mA) | Voc (V) | FF | Pmax (mW) | Iph (mA) | I0 (A) (E) | Rsh (Ω) | Rs (Ω) | n |
---|---|---|---|---|---|---|---|---|---|
0 | 3.92 | 0.280 | 0.604 | 0.663 | 3.96 | 2–7 | 1,500 | 5.5 | 1.114 |
1 × 1012 | 3.13 | 0.215 | 0.553 | 0.371 | 3.13 | 1.7–6 | 1,100 | 5.6 | 1.115 |
5 × 1012 | 2.74 | 0.140 | 0.493 | 0.189 | 2.79 | 1.8–5 | 900 | 5.7 | 1.114 |
Changes in the remaining factor of Isc, Voc, Pmax, and FF of In0.53Ga0.47As solar cells before and after differing proton fluence irradiation levels are shown in the curves of
The displacement damage caused by proton irradiation is mainly responsible for the degradation of In0.53Ga0.47As solar cells’ performance and electrical parameters. When solar cells are under proton irradiation, the incident proton interacted with atoms on the pristine lattice position and transferred energy to the atoms by elastic or inelastic collisions, which removed atoms from their initial position, causing large amounts of defects [
Schematic diagram of irradiation-induced defect levels in band structure.
The degradation of Isc is mainly due to the displacement damage defects induced by proton irradiation in the active region of solar cells. There are two main mechanisms that cause the degradation of solar cell performance. First, the displacement damage generates non-irradiative recombination centers (defect level Ⅱ in
The EQE spectra of 150 KeV proton-irradiated In0.53Ga0.47As solar cells is shown
Thermal annealing experiments were then carried out on In0.53Ga0.47As single junction solar cells irradiated by 150 KeV proton with doses of 5 × 1012 p/cm2; the annealing temperature was set to 150°C. For the purpose of evaluating the influence of annealing time, the duration of annealing was set to 20, 60, 120, 180, and 360 min.
The variation of electrical parameters
After annealing at 150°C, the performance of In0.53Ga0.47As solar cells irradiated by protons was obviously restored. There are two possible reasons for this phenomena. First, during the annealing process, a large number of carriers are generated inside the In0.53Ga0.47As solar cell, which induce a “carrier injection annealing effect”, and some proton irradiation-induced defects were annihilated. This consequently increased the minority carrier life and the performance of the In0.53Ga0.47As solar cell could be restored [
In the present article, In0.53Ga0.47As single junction solar cells were subjected to 150 KeV proton radiation with different fluence. In order to understand low-energy proton irradiation-induced displacement damage distribution in In0.53Ga0.47As single junction solar cells, SRIM simulations were firstly carried out to simulate the trajectories of 105 incident protons and the induced trap density. And the corresponding electrical and spectral properties after irradiation were well characterized by experimental means. The sequential annealing process from 20 to 360 min were then implemented to reveal the recovery of cell performance correlated with the thermal annealing treatments. The results show that most protons would penetrate through InGaAs emitter and stop in InGaAs base region, causing differing extents of electric and spectral degradation. When proton fluence was 1 × 1012 and 5 × 1012 p/cm2, the remaining factor of Isc, Voc, Pmax, and FF were degraded to 0.790, 0.767, 0.558, 0.921 and 0.697, 0.500, 0.285, 0.817, respectively. Severer degradation of short wave lengths then long wave lengths of the solar cell spectral response was observed. After annealing for different time at 150°C, it was shown that significant recovery of cell performance occurred after annealing for 20 min, and there is no obvious substantial recovery in continuous annealing up to 360 min. And the recovered degree of the short wavelength of the solar cell was greater than in the long wavelength, which reveals the fact that the defects induced by proton irradiation in the whole emission area and part of the base area were annihilated. Our performance analysis could provide evidence for the proper design of annealing cycles for space missions to enhance the performance of solar cells in space.
The data that supports the findings of this study are available from the corresponding author upon reasonable request.
YZ, AA, and QL designed the research, conducted the experiments and wrote this manuscript. All authors contributed to the discussion of the results and edited the manuscript.
Author LF was employed by the company Uniwatt Technology Co. Ltd. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
This work was supported by Basic Research Foundation of Yunnan Province(Grant number: 202001AU070090), a key project of the Natural Science Foundation of China (Grant number: 61534008), and Doctoral Start-up Funding of Yunnan Normal University (Gran number: 2019XJLK05/01700205020503040).