Abstract
Achieving a cheap and ultrafast metal-semiconductor-metal (MSM) photodetector (PD) for very high-speed communications is ever-demanding. We report the influence of anodization current density variation on the response of nanoporous silicon (NPSi) based MSM PD with platinum (Pt) contact electrodes. Such NPSi samples are grown from n-type Si (100) wafer using photoelectrochemical etching with three different anodization current densities. FESEM images of as-prepared samples revealed the existence of discrete pores with spherical and square-like shapes. XRD pattern displayed the growth of nanocrystals with (311) lattice orientation. The nanocrystallite sizes obtained using Scherrer formula are found to be between 20.8 nm and 28.6 nm. The observed rectifying behavior in theI-Vcharacteristics is ascribed to the Pt/PSi/n-Si Schottky barrier formation, where the barrier height at the Pt/PSi interface is estimated to be 0.69 eV. Furthermore, this Pt/PSi/Pt MSM PD achieved maximum responsivity of 0.17 A/W and quantum efficiency as much as 39.3%. The photoresponse of this NPSi based MSM PD demonstrated excellent repeatability, fast response, and enhanced saturation current with increasing anodization current density.
Highlights
Canham’s [1] discovery on the room temperature visible photoluminescence (PL) from porous silicon (PSi) generated intense research interests towards the synthesis and characterization of Si nanostructures (NSs) in general and nanoporous silicon (NPSi) in particular
Sample grown at 25 mA/cm2 anodization current density (Figure 1(b)) displayed substantially wider pores, which are irregular across the entire surface
Sample grown at 35 mA/cm2 anodization current density (Figure 1(c)) exhibited highly porous nature with columnar structure, which is uniform across the entire surface
Summary
Canham’s [1] discovery on the room temperature visible photoluminescence (PL) from porous silicon (PSi) generated intense research interests towards the synthesis and characterization of Si nanostructures (NSs) in general and nanoporous silicon (NPSi) in particular. These spectra of research activities are mainly targeted to achieve Si nanomaterials with desired band gap useful for efficient optoelectronic applications [2,3,4]. Nanosilicon research is triggered because of technological implication and to unravel the fundamental mechanism, socalled quantum confinement effect, which is responsible for the energy band gap enhancement [7, 8]. These properties are beneficial for making photodetectors [9, 10]
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