A CdSe quantum dot photodetector for hyperspectral imaging in the visible region

A spectrally resolving quantum dot photodetector has been designed and fabricated which is able to discriminate wavelengths in the visible region. The device consists of a monolayer of 5.4 nm diameter CdSe nanoparticles that have been sandwiched between two organic layers of Hexanedithiol, all on a highly doped p-type InP substrate. A thin, semitransparent layer of gold deposited on the top of the device made the second contact. The two layers of Hexanedithiol act as tunnel barriers for electrons inside the nanoparticles. Changing the bias voltage across the device, causes specific energy states inside the quantum dot to align with the conduction band edge of the InP. Any excited carriers in these energy levels will tunnel trough the organic barrier and be collected as photocurrent. The responsivity and noise equivalent power has been measured for two wavelengths.