Size-dependent photocurrent of photodetectors with silicon nanocrystals

Abstract

We report on the effect of nanocrystal size on the photocurrent of silicon nanocrystal ͑Si NC͒ photodetectors. The photocurrent onset energy was increased with decreasing the size of Si NCs, which agreed with the blueshift in the absorption onset. The increase in the quantum efficiency with increasing the size of Si NCs was much larger than the increase in the absorbance with increasing the size of Si NCs. This was attributed to the differences in charge separation for Si NC of different sizes, which was influenced by the recombination rate and binding energy of photogenerated excitons in Si NCs.

Graphene/Si‐Quantum‐Dot Heterojunction Diodes Showing High Photosensitivity Compatible with Quantum Confinement Effect

“…The R i spectra were also measured for graphene/≈4 nm SiO 2 /n-Si structures and were found to be very similar to those of commercially available Si PDs ( Figure S14, Supporting Information), suggesting that the photoresponse of the structures without SQDs is strongly infl uenced by the Si substrate. [ 32 ] The QE in the visible range (≈600 nm) reaches ≈72% at n D = 20 × 10 −3 M , much larger than those reported for graphene/bulk-Si, [ 11 ] metal/SQD, [ 33 ] and metal/II-VI-QD PDs. The spectral QE shows similar behaviors with the spectral R i , except a small difference between their peak wavelengths, as shown at a bias of -3 V in Figure 2 e (for other biases, see Figure S13, Supporting Information), resulting from the strong absorption of the SQDs in the high-energy side.…”

Size effect on electronic transport in nC–Si/SiO core/shell quantum dots

“…Quantum confinement is known to alter the electrical conductivity in Si-NCs [9,10]. Possible applications in numerous other fields e.g., in photovoltaics [11], photodetectors [12], data storage [13] and optical waveguide [14] have also been demonstrated.…”

Size and temperature dependence of the energy gaps in Si, SiC and C quantum dots based on tight-binding molecular dynamics simulations

“…Si quantum dots for optical applications have been made using several epitaxial methods, and the energy gaps have been analyzed. According to photoluminescence (PL) experiments, the peak energies of PL spectra corresponding to the energy gaps increase as the quantum dot size decreases [12][13][14][15][16][17]. This is explained with the effective mass theory, using a semi-classical or semi-quantum approach, in which the peak energies of PL vary as 1/D 2 with the diameter D of the quantum dot.…”