Nanocrystalline cadmium selenide(nc-CdSe) particles were potentiostatically deposited within a nanoscale Au electrode gap. We accessed the properties of this Au-CdSe-Au junction for detecting light as photoconductors. Structural characterizations with XRD, EDX, TEM and Raman spectroscopy revealed that they were composed of stoichiometric, single phase, cubic CdSe with a mean grain diameter about 7 nm. Optical absorption and photoluminescence spectra were both dominated by band-edge transition. Photocurrents, iphoto, of 10-100 � idark, were achieved with a spectral response characterized by an onset of 1.75 eV. By optimizing the gap size and sample preparation, the device demonstrated a significantly higher photoconductive gain (~1000) than the value with CdSe nanowire based devices we reported earlier. The response or recovery time was very short, below 2.5 �s, corresponding to the -3dB bandwidth of 140 kHz, limited by the measurement circuit. Furthermore, by depositing different kinds of materials, the detector is highly tunable to the wavelength of interest. 

Nanoscale photoconductors with high gain and bandwidth

243rd National Meeting (2012)

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