Ultrahigh Responsivity Visible and Infrared Detection Using Silicon Nanowire Phototransistors

Zhang, Arthur; Kim, Hongkwon; Cheng, James; Lo, Yu‐Hwa

doi:10.1021/nl1006432

Cited by 140 publications

(121 citation statements)

References 20 publications

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“…[11][12][13][14][15][16] Among such systems, ZnO has always stood out due to its attractive wide band gap (3.37 eV at room temperature) with a high exciton binding energy (60 meV), which makes it appropriate for short wavelength optoelectronic applications, such as ultra-violet (UV) detectors, and UV and blue light emitting devices. 11,17,18 Despite the extensive research and the achieved progress, the integration of ZnO nanowires as a complete optoelectronic device is still a challenge.…”

Section: Introductionmentioning

confidence: 99%

ZnO UV photodetector with controllable quality factor and photosensitivity

et al. 2013

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ZnO nanowires have an enormous potential for applications as ultra-violet (UV) photodetectors. Their mechanism of photocurrent generation is intimately related with the presence of surface states where considerable efforts, such as surface chemical modifications, have been pursued to improve their photodetection capabilities. In this work, we report a step further in this direction demonstrating that the relative photosensitivity and quality factor (Q factor) of the photodetector are entirely tunable by an applied gate voltage. This mechanism enables UV photodetection selectivity ranging from wavelengths from tens of nanometers (full width at half maximum - FWHM) down to a narrow detection of 3 nm. Such control paves the way for novel applications, especially related to the detection of elements that have very sharp luminescence

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Section: Introductionmentioning

confidence: 99%

ZnO UV photodetector with controllable quality factor and photosensitivity

et al. 2013

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“…where n 0 is the carrier density in the dark [20]. To estimate Δn we use the change in the photoconductivity of the nanowires as derived from the analysis above.…”

Section: Resultsmentioning

confidence: 99%

Role of Contact and Contact Modification on Photo-response in a ChargeTransfer Complex Single Nanowire Device

Basori

Raychaudhuri

2014

Nano-Micro Lett

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Abstract:We investigated the feasibility of obtaining large photoresponse in metal-semiconductor-metal (MSM) type single nanowire device where one contact can be blocking type. We showed that suitable modification of the blocking contact by deposition of a capping metal using focused electron beam (FEB) can lead to considerable enhancement of the photoresponse. The work was done in a single Cu:TCNQ nanowire device fabricated by direct growth of nanowires (NW) from pre-patterned Cu electrode which makes the contact ohmic with the other contact made from Au. Analysis of the data shows that the large photoresponse of the devices arises predominantly due to reduction of the barriers at the Au/NW blocking contact on illumination. This is caused by the diffusion of the photo generated carriers from the nanowires to the contact region. When the barrier height is further reduced by treating the contact with FEB deposited Pt, this results in a large enhancement in the device photoresponse.

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“…The silicon nanowires were synthesized by the typical gold-catalyzed vapor-liquid-solid (VLS) process in a mixture of H 2 -balanced SiH 4 and BH 3 . To make contacts to single nanowires, we first prepared a nanowire suspension by sonicating the as-grown nanowire samples in isopropanol (IPA) followed by a proper cleaning process (17).…”

Section: Methodsmentioning

confidence: 99%

Optoelectronically probing the density of nanowire surface trap states to the single state limit

Dan

2015

Applied Physics Letters

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Due to the large surface-to-volume ratio, surface trap states play a dominant role in the optoelectronic properties of nanoscale devices(1-6). Understanding the surface trap states allows us to properly engineer the device surfaces for better performance. But characterization of surface trap states at nanoscale has been a formidable challenge using the traditional capacitive techniques based on metal-insulator-semiconductor (MIS) structures(7) and deep level transient spectroscopy (DLTS)(8-11). Here, we demonstrate a simple but powerful optoelectronic method to probe the density of nanowire surface trap states to the limit of a single trap state. Unlike traditional capacitive techniques (Fig1a), in this method we choose to tune the quasi-Fermi level across the bandgap of a silicon nanowire photoconductor, allowing for capture and emission of photogenerated charge carriers by surface trap states (Fig1b). The experimental data show that the energy density of nanowire surface trap states is in a range from 10 9 cm -2 /eV at deep levels to 10 12 cm -2 /eV in the middle of the upper half bandgap. This optoelectronic method allows us to conveniently probe trap states of ultra-scaled nano/quantum devices at extremely high precision.To understand this method, let us use p-type semiconductors as an example. A highly doped ptype semiconductor has an extremely high concentration of holes but a very low concentration of electrons. Under illumination, excess electrons and holes are generated in the conduction and valence band, respectively. At small injection condition, these excess carriers are negligibly low in concentration compared to the majority holes, but often orders of magnitude larger than the minority electrons. Consequently, the quasi-Fermi level of electrons ( ) shifts away significantly from the Fermi level at equilibrium ( ), while the quasi-Fermi level of holes ( ) remains nearly unchanged as , as shown in Fig.1b. In general, the shift of quasi-Fermi levels leads to filling the trap states below (but above ) with electrons, and those above (but below ) with holes. Clearly, for a highly doped p-type semiconductor at small injection condition, only the minority electrons get involved in the capture-emission process of trap states. For every photogenerated electron captured by trap states, there is one corresponding hole remaining in the valence band to contribute to photoconductance. The shift of will allow a large number of electrons to be trapped if the density of trap states, at deep levels in particular, is high, leading to the giant gain in photoconductance that has been widely observed(1-3).

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Ultrahigh Responsivity Visible and Infrared Detection Using Silicon Nanowire Phototransistors

Cited by 140 publications

References 20 publications

ZnO UV photodetector with controllable quality factor and photosensitivity

ZnO UV photodetector with controllable quality factor and photosensitivity

Role of Contact and Contact Modification on Photo-response in a ChargeTransfer Complex Single Nanowire Device

Optoelectronically probing the density of nanowire surface trap states to the single state limit

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