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Professor Rachel Oliver

Research Interests

Nitrides at the nanoscale

Working in the Cambridge GaN centre, my research focuses on the characterization and exploitation of nanoscale structures in GaN-based materials. The broad aim of my work is to achieve improved performance in GaN-based optoelectronic devices and to develop and implement novel device concepts.

Novel microscopy techniques for nitride semiconductors

To improve the performance of GaN-based devices we need to understand their structure and electronic properties on a micro- to nano-metre scale. New techniques are being developed to meet the demands of this unusual semiconductor. Our work involves: (a) applications of atomic-force microscopy (AFM) to studies not only of nitride surface topography but also of the electrical properties of nitride materials at length scales as small as 10 nm; and (b) exploiting the three-dimensional atom-probe microscope (3DAP) to determine the composition of GaN alloys, particularly InGaN quantum wells, in 3D, at a sub-nanometre scale.

GaN-based single photon sources

Early single-photon sources emitting in the visible spectral region were based on heavy attenuation of a laser; such sources are intrinsically unreliable, and may emit multiple photons. In contrast, we aim to build a single-photon source, based on InGaN quantum dots, that is reliable and easy to operate. Such a device would find broad application in quantum cryptography and quantum computing, particularly as the emission wavelength of the InGaN dots is rather convenient in terms of available detectors. However, the high defect density and unusual electrical properties of GaN make realising the device a challenge.