# In/GaN(0001)-$\boldsymbol{{\mathsf{\left(\!\sqrt{3}\times\!\sqrt{3}\right)\!R30^{\circ}}}}$ adsorbate structure as a template for embedded (In,Ga)N/GaN monolayers and short-period superlattices

## TL;DR

This paper presents a novel method for fabricating (In,Ga)N/GaN superlattices using a specific In adsorbate surface reconstruction as a template, resulting in high-quality, monolayer-thick quantum sheets with predictable optical properties.

## Contribution

It introduces a new epitaxial approach leveraging a surface reconstruction to create embedded monolayer quantum sheets in superlattices with controlled composition and interface quality.

## Key findings

- Successful synthesis of (In,Ga)N/GaN superlattices with abrupt interfaces.
- Embedded quantum sheets contain 0.25-0.29 In content.
- Photoluminescence at 3.16 eV matches theoretical predictions.

## Abstract

We explore an alternative way to fabricate (In,Ga)N/GaN short-period superlattices on GaN(0001) by plasma-assisted molecular beam epitaxy. We exploit the existence of an In adsorbate structure manifesting itself by a $(\sqrt{3}\times\!\sqrt{3})\text{R}30^{\circ}$ surface reconstruction observed in-situ by reflection high-energy electron diffraction. This In adlayer accommodates a maximum of 1/3 monolayer of In on the GaN surface and, under suitable conditions, can be embedded into GaN to form an In$_{0.33}$Ga$_{0.67}$N quantum sheet whose width is naturally limited to a single monolayer. Periodically inserting these quantum sheets, we synthesize (In,Ga)N/GaN short-period superlattices with abrupt interfaces and high periodicity as demonstrated by x-ray diffractometry and scanning transmission electron microscopy. The embedded quantum sheets are found to consist of single monolayers with an In content of 0.25-0.29. For a barrier thickness of 6 monolayers, the superlattice gives rise to a photoluminescence band at 3.16 eV, close to the theoretically predicted values for these structures.