Suppression of the thermal quenching of photoluminescence in irradiated silicon heterojunction solar cells

Abstract

We report on the decrease in photoluminescence (PL) intensity with the increase of the sample temperature (thermal quenching) in crystalline silicon and its suppression after ion irradiation. The crystalline silicon surface was passivated with intrinsic and doped hydrogenated amorphous silicon (a-Si:H) layer stacks as for making silicon heterojunction solar cell precursors. Low energy argon ion irradiation, in the range between 5 and 17 keV, was used for controlled defect formation either in the thin a-Si:H top layer or at the interface with the crystalline silicon beneath. The irradiation defects introduce radiative recombination centers in the a-Si:H as can be measured from PL at low temperature. Moreover, the irradiation and annealing result in a strong modification of the thermal quenching of the PL intensity up to 500 K, showing evidence for the strong reduction of thermally activated nonradiative recombinations at the amorphous-crystalline interface. This result can have implications in the field of crystalline silicon surface passivation.

Defect State Analysis in Ion‐Irradiated Amorphous‐Silicon Heterojunctions by HAXPES

“…In particular, this technique has allowed to identify defect‐induced states on a‐Si:H heterostructures . Photoluminescence in different a‐Si:H heterostructures shows two main peaks . The most intense peak at 1.1 eV corresponds to the band to band recombination in c‐Si (1.1 eV).…”

“…The a‐Si:H and a‐SiC:H were deposited by plasma‐enhanced chemical vapor deposition (PECVD) method at 200 °C in the ARCAM reactor . Once the heterostructure was produced by PECVD, defects were introduced by implanting 1 keV of Ar + ions in a microwave source plasma reactor . The Ar + fluence was controlled to 10 15 Ar cm −2 .…”

“…[11,12] Photoluminescence in different a-Si:H heterostructures shows two main peaks. [9,13] The most intense peak at 1.1 eV corresponds to the band to band recombination in c-Si (1.1 eV). A broader and less intense peak appears at 1.2 eV, an energy smaller than the band gap of hydrogenated amorphous Si (1.7 eV) that must be associated to defect states within its gap.…”

“…[16] Once the heterostructure was produced by PECVD, defects were introduced by implanting 1 keV of Ar þ ions in a microwave source plasma reactor. [13] The Ar þ fluence was controlled to 10 15 Ar cm À2 .…”