Quantum-Well Photoemission Media for Terabit/inch^2 Ultrahigh-Density Optical Storage Employing Probe-Collection Tunneling-Electron Luminescence(Optics and Quantum Electronics)

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For terabit/inch^2 ultrahigh-density optical storage with a pit size of less than 25-nm square, we propose probe collection of tunneling-electron luminescence (TL) as a new pickup method. In this method, a probe injects tunneling electrons into a nanometer-sized region in the photoemission medium and the same probe simultaneously collects TL from that region. A semiconductor single quantum well (SQW) has been developed as a photoemission medium that is well-matched with this method. The key features of the SQW medium are (1) a high p-type doping concentration of 2 × 10^<19>cm^<-3> that maximizes the internal quantum efficiency, (2) a flat valence-band edge between the substrate and well for smooth supply of holes to the well, and (3) optimal well depth to maximize probe collection efficiency. Experimental results clarified that tunneling electrons are much better than light for injecting powers into the thin SQW to induce the luminescence, and the use of the SQW instead of bulk material increases the TL intensity at least six times. The TL intensity increases in proportion to tunnel current without saturation at least up to about 30nA. Consequently, the combination of probe-collection TL with the SQW is believed to be suitable for terabit/inch^2 ultrahigh-density optical storage, which requires intense photoemission from nanometer-sized pits.
社団法人応用物理学会の論文
2002-06-15