David Cecil Hays

Epitaxial growth of 20 nm InAs and GaAs quantum dots on GaAs through block copolymer templated SiO2 masks

We report on selective area growth of InAs and GaAs quantum dots (QDs) on GaAs through ∼20u2002nm SiO2 windows prepared by block copolymer lithography. We discuss the mechanisms of growth through these masks, highlighting the variation of the resulting morphology (dot size, spacing, uniformity, and areal density) as a function of growth parameters. We have obtained highly uniform arrays of InAs and GaAs QDs with mean diameters and areal densities of 20.6 nm and 1×1011u2002cm−2, respectively. We have also investigated the optical characteristics of these QDs as a function of temperature and drawn correlations between the optical response and their crystalline quality.

Infrared p-i-n photodiodes based on InAs quantum dots grown on 20 nm patterned GaAs

We report on selective area growth of InAs quantum dots on GaAs substrates patterned with a hexagonal array of 20 nm pores using block copolymer lithography. We discuss the mechanisms of growth, highlighting the variation in the resulting morphology as a function of nucleation enhancing AlGaAs layers. We also evaluate the optoelectronic performance of p-i-n photodiodes based on single layer nanopatterned grown InAs quantum dot devices. At low to moderate reverse biases, we observe room temperature photoresponse in both near- and mid-IR regimes. At high biases, we observe strong avalanche effects in the mid-IR range with a gain factor of ∼4000.