Indium‐Doped Silicon for Solar Cells—Light‐Induced Degradation and Deep‐Level Traps

Joyce Ann T De Guzman,Ian D Hawkins,Iain F Crowe,Robert Falster,Hussein M Ayedh,José Coutinho,Nikolay V Abrosimov,Jeff Binns,Anthony R Peaker,Vladimir P Markevich,Matthew P Halsall

doi:10.1002/pssa.202100108

Abstract

Indium‐doped silicon is considered a possible p‐type material for solar cells to avoid light‐induced degradation (LID), which occurs in cells made from boron‐doped Czochralski (Cz) silicon. Herein, the defect reactions associated with indium‐related LID are examined and a deep donor is detected, which is attributed to a negative‐U defect believed to be InsO2. In the presence of minority carriers or above bandgap light, the deep donor transforms to a shallow acceptor. An analogous transformation in boron‐doped material is related to the BsO2 defect that is a precursor of the center responsible for BO LID. The electronic properties of InsO2 are determined and compared to those of the BsO2 defect. Structures of the BsO2 and InsO2 defects in different charges states are found using first‐principles modeling. The results of the modeling can explain both the similarities and the differences between the BsO2 and InsO2 properties.

Highlights

Indium-doped silicon has been proposed as a possible p-type material for solar cells to avoid light-induced degradation (LID) observed in boron-doped Czochralski (Cz) silicon
We have found that the electronic characteristics of the defect, which gives rise to this signal in indium-doped continuous Cz growth (CCz)-Si, are similar to the ones for an analogous defect detected in the diodes fabricated from Cz-Si doped with boron atoms
Our experimental data have shown that a minority carrier trapping center is present in the CCz-grown silicon doped with indium atoms

Summary

Introduction

Indium-doped silicon has been proposed as a possible p-type material for solar cells to avoid light-induced degradation (LID) observed in boron-doped Czochralski (Cz) silicon. The literature contains conflicting reports of LID in indium-doped material.[1,2,3,4,5,6,7,8] The situation is complicated by the incomplete ionization of indium resulting from its high activation energy of about 160 meV for hole minority carrier lifetime stability of Si:In slices under illumination with that for boron, gallium, and aluminum-doped silicon and only observed LID in Si:B.[1] The Si:In had a resistivity of 14.5 Ω cm and an oxygen content of %7 Â 1017 cmÀ3.[12] Binns et al.[7] observed no measurable change in minority carrier lifetime in CCz Si:In with a resistivity of 3.8 Ω cm and [Oi] of (6.0 Æ 0.4) Â 1017 cmÀ3 after outdoor light soaking with a total irradiance of %10 kWh mÀ2. The unionized indium fraction acts as a recombination doped materials showed a degradation of lifetime from 160 to

Results

Discussion

Conclusion