Mechanical Nano-Patterning: Toward Highly-Aligned Ge Self-Assembly on Low Lattice Mismatched GaAs Substrate

Ghada Dushaq, Mahmoud Rasras

Research output: Contribution to journalArticlepeer-review


Low-dimensional semiconductor structurers formed on a substrate surface at pre-defined locations and with nano-precision placement is of vital interest. The potential of tailoring their electrical and optical properties will revolutionize the next generation of optoelectronic devices. Traditionally, highly aligned self-assembly of semiconductors relies on Stranski- Krastanov growth mode. In this work, we demonstrate a pathway towards ordered configuration of Ge islands on low lattice mismatch GaAs (110) substrate patterned using depth-controlled nanoindentation. Diamond probe tips with different geometries are used to nano-mechanically stamp the surface of GaAs (110). This creates nanoscale volumes of dislocation-mediated deformation which acts to bias nucleation. Results show that nanostamped GaAs exhibits selective-nucleation of Ge at the indent sites. Ge islands formed on a surface patterned using cube corner tip have height of ~10 nm and lateral size of ~225 nm. Larger islands are formed by using Vickers and Berkovich diamond tips (~400 nm). The strain state of the patterned structures is characterized by micro-Raman spectroscopy. A strain value up to 2% for all tip geometries has been obtained. Additionally, strong room temperature photoluminescence (PL) emission is observed around 1.9 µm (650 meV). The observed strain-induced enhancement in the light-emission efficiency is attributed to direct conduction to heavy-hole (cΓ-HH) and conduction to light-hole (cΓ-LH) transitions. The inherent simplicity of the proposed method offers an attractive technique to manufacture semiconductor quantum dot structures for future electronic and photonic applications.

Original languageEnglish (US)
Article number14221
JournalScientific reports
Issue number1
StatePublished - Dec 1 2019

ASJC Scopus subject areas

  • General


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