Local Droplet Etching with Indium Droplets on InP(100) by Metal-Organic Vapor Phase Epitaxy

Abstract

The local droplet etching (LDE) by using indium droplets on bare InP(100) surfaces is demonstrated in a metal-organic vapor phase epitaxy (MOVPE) environment for the first time. The role of an arsenic flow applied to self-assembled metallic indium droplets is systematically studied. Increasing the arsenic supply leads to the formation of ring-like nanostructures and nanoholes. The results are analyzed with reference to LDE in a molecular beam epitaxy environment, where such a technique is well established, particularly for arsenide-based III-V semiconductors, and where only one group-V material is involved. Here, As-P exchange reactions at droplet sites are identified as the drivers for the formation of nanoholes. Such nanoholes can serve as nucleation sites for subsequent fabrication of highly symmetric QDs by nanohole-infilling or as a means for in situ surface nanopatterning. LDE on InP by MOVPE can thus be considered as a promising approach for the cost-effective fabrication of novel quantum emitters at the telecom C-band.

Figure 1

5 × 5 μm² AFM micrographs of the four samples studied in this work corresponding to increasing As flow from 0.1 to 10 sccm (A–D).

Figure 2

3D AFM micrographs of selected structures from samples A–D with variation of As supply: (A) 0.1 sccm: indium droplet, (B) 0.5 sccm: nanoring-shaped structures, (C) 3 sccm: initial formation of etch pits with thin walls, and (D) 10 sccm: etch pits with shallow walls.

Figure 3

Densities of the nanostructures with varying arsenic flow for samples A–D and the reference sample without an arsenic supply.

Figure 4

AFM micrographs and profiles of selected structures of samples A–D.

Figure 5

TEM micrographs of samples A–D.

Figure 6

TEM micrograph of sample B. The red dotted lines highlight the profile of the capped ring structure.

Figure 7

PL spectra of all investigated samples recorded at (a) room temperature and (b) at 4 K.

Figure 8

Sketch of the stages of the LDE process from droplet (A) to nanohole formation (C, D) through ring formation (B). The circles represent the atoms involved in the process as follows: As (yellow), In (red), and P (blue). The orange triangles are the InAs crystallized structures.