Detection of single photons using a field-effect transistor gated by a layer of quantum dots

Abstract

We demonstrate that the conductance of a field-effect transistor ͑FET͒ gated by a layer of nanometer-sized quantum dots is sensitive to the absorption of single photons. Rather than relying upon an avalanche process, as in conventional semiconductor single-photon detectors, the gain in this device derives from the fact that the conductivity of the FET channel is very sensitive to the photoexcited charge trapped in the dots. This phenomenon may allow a type of three-terminal single-photon detector to be developed based upon FET technology. © 2000 American Institute of Physics. ͓S0003-6951͑00͒01525-4͔Time-resolved single-photon detection is required for such diverse applications as medical diagnosis and imaging, chemical analysis, laser ranging, and materials characterization. 1 Photonic technology is also important for future applications in optical quantum cryptography and computing. Conventionally, single photons are detected by multiplication of a photogenerated carrier by an avalanche process, either in a vacuum photomultiplier tube, or, in the case of the semiconductor avalanche photodiode, a reversebiased junction ͑see, for example, Refs. 1-3͒. Here, we propose and demonstrate detection of single photons based upon an entirely different principle using a field-effect transistor ͑FET͒ containing quantum dots.Self-organizing growth techniques, based upon carefully controlled strained layer epitaxy, allow the formation of a high density of quantum dots with nanometer dimensions and relatively homogeneous size distribution. A particularly attractive aspect of this technique is that it can be used to produce quantum-dot layers within an epitaxially grown device structure. It has been shown that such a layer of selfassembled quantum dots can radically alter the transport properties of a nearby two-dimensional electron gas ͑2DEG͒. 4-6 Under illumination the quantum dots can trap photoexcited carriers, providing the possibility of using such dots as an optically addressed data storage medium. 7-11 Such structures have also been demonstrated as nonquantum detectors of midinfrared radiation through excitation of the bound-to-continuum intersubband photoconductivity. 12 It has been proposed 7 and demonstrated 8,10 that the inhomogeneous broadening of the quantum-dot optical transitions can be used to store more than one bit of information at each laser spot position, by tuning the laser wavelength to access dots with different transition energies. This requires a scheme to detect the presence of photoexcited charge in a single ͑or just a few͒ quantum dot. The results presented here demonstrate that by using a FET structure it is indeed possible to detect the presence of a single photoexcited carrier in a single quantum dot. Figure 1 shows a schematic of the device structure. It consists of a GaAs/Al 0.33 Ga 0.67 As modulation-doped FET containing a layer of InAs quantum dots separated from the 2DEG in the GaAs channel by a thin Al 0.33 Ga 0.67 As barrier. Since there are bound states of the quantum dots lying to lower ...

Self-assembled InAs quantum dot formation on GaAs ring-like nanostructure templates

“…In recent times, semiconductor quantum dots (QDs) have attracted increased attention because of their potential application in optoelectronic devices, such as, for quantum computation [1], lasers [2], single photon sources [3][4][5], charge storage devices [6] and single photon detectors [7]. Because of the need to control the size, shape, and distribution of these zero-dimensional structures, much effort has been put forth to fabricate QDs with uniformity and precision.…”

Nonlinear quantum optical computing via measurement

“…Current proposals for detectors range from novel mesoscopic electronic devices [17], and superconducting devices [18] to novel systems that use stimulated Raman scattering [19,20] and EIT [21] The technology that might deliver a Kerr nonlinear device with the required strength is more difficult to identify. Recent progress in EIT schemes [22,23,24,25] and cavity QED processes [26,27] may offer some hope.…”

EPR Beams and Photon Number Detector: Toward Synthesizing Optical Nonlinearity

“…For the visible light region, there is a nice device called VLPC which has a very high quantum efficiency, and could directly observe nonclassical light statistics [6]. There are also several other candidates based on sophisticated mechanisms, such as quantum dot array FET [7], and the superconducting edge sensor [8]. Recently another practical scheme has been demonstrated, which is based on cascading commercially available Si-APDs [9,10].…”