GaN intermediate band solar cells with Mn-doped absorption layer

Ming-Lun Lee,Po-Cheng Chen,Feng-Wen Huang,Jinn-Kong Sheu

doi:10.1038/s41598-018-27005-z

Abstract

The effect of Mn concentration on the optical properties of Mn-doped layers grown by metalorganic vapor phase epitaxy is investigated. The Mn-doped GaN layers exhibite a typical transmittance spectrum with a distinct dip around 820 nm which is attributed to the transition of electrons between the edge of valence band and the Mn-related states within the bandgap. In addition, electroluminescence (EL) spectra obtained from the bipolar devices with Mn-doped GaN active layer also show that considerable Mn-related energy states existed in the bandgap. The position of the Mn-related energy states in the GaN is first evaluated via EL spectra. In addition to the absorption of band edge, the Mn-related energy states behaving like an intermediate band cause an additional sub-band gap absorption. Consequently, the fabricated GaN-based solar cells using Mn-doed GaN as the absorption layer exhibit photocurrent higher than the control devices without Mn doping. Under one-sun air mass 1.5 G testing condition, the short-circuit current of the Mn-doed GaN solar cells can be enhanced by a magnitude of 10 times compared with the cells without Mn doping.

Highlights

The effect of Mn concentration on the optical properties of Mn-doped layers grown by metalorganic vapor phase epitaxy is investigated
Theoretical work conducted by Martí et al has predicted that InxGa1−xN-based solar cell doped with Mn as an intermediate band (IB) material could achieve a maxima efficiency of 53.4% when the Mn atomic concentration exceeds 6 × 1019 cm−3 9.interest in the Mn-doped GaN has been driven by the theoretical proposal of an innovative type of solar cell, namely, an intermediate-band solar cell (IBSC)[9]
The Mn-doping control in GaN that depends on growth parameters is still lacking, the significant diffusion and memory effect of Mn dopants in GaN grown by metalorganic vapor phase epitaxy (MOVPE) have been reported in the literature[26]

Summary

Introduction

The effect of Mn concentration on the optical properties of Mn-doped layers grown by metalorganic vapor phase epitaxy is investigated. Electroluminescence (EL) spectra obtained from the bipolar devices with Mn-doped GaN active layer show that considerable Mn-related energy states existed in the bandgap. The fabricated GaN-based solar cells using Mn-doed GaN as the absorption layer exhibit photocurrent higher than the control devices without Mn doping. The GaN-based materials doped with Mn have recently attracted considerable attention because they exhibit ferromagnetism above room temperature (RT)[1,2,3]. This property can potentially provide new functionalities and enhanced performance in conventional electronic devices operating at RT4–7. The effect of Mn doping concentration on the optical properties of Mn-doped GaN layers is systematically investigated, and GaN-based solar cells with Mn-doped absorption layer are characterized

Methods

Results

Conclusion