Half-filled intermediate bands Si material formed by energetically metastable interstitial sulfur atom

TL;DR

This paper introduces a high-throughput computational method to identify metastable sulfur states in silicon, revealing many states that form a half-filled intermediate band suitable for IB solar cells.

Contribution

The study develops a novel first-principles approach to systematically find metastable interstitial sulfur states in silicon, identifying 63 states with potential for solar cell applications.

Findings

63 metastable sulfur states identified in silicon

44% of these states form a half-filled intermediate band

Potential application in intermediate band solar cells

Abstract

Hyperdoped metastable sulfur atoms endow crystalline silicon with a strong sub-bandgap light absorption. In order to explore such metastable states, we develop a new high-throughput first-principles calculation method to search for all of the energetically metastable states for an interstitial sulfur atom inside crystalline silicon. Finally, we obtain sixty-three metastable interstitial states and they can be classified into ten types. Interestingly, twenty-eight (44% in total) of lower-energy metastable states can produce a well-isolated and half-filled intermediate band (IB) inside silicon forbidden gap, which makes sulfur hyperdoped silicon to be a desirable material for IB solar cells.