Controlled blueshift of the resonant wavelength in porous silicon microcavities using ion irradiation

Abstract

High-energy focused proton beam irradiation has been used to controllably blueshift the resonant wavelength of porous silicon microcavities in heavily doped p-type wafers. Irradiation results in an increased resistivity, hence a locally reduced rate of anodization. Irradiated regions are consequently thinner and of a higher refractive index than unirradiated regions, and the microcavity blueshift arises from a net reduction in the optical thickness of each porous layer. Using this process wafers are patterned on a micrometer lateral scale with microcavities tuned to different resonant wavelengths, giving rise to high-resolution full-color reflection images over the full visible spectrum.

Silicon Nanocrystals in Porous Silicon and Applications

“…DBRs with submicrometer lateral dimensions have been demonstrated using focused ion beam technology to locally alter the Si substrate resistivity prior to anodization [45]. The technique has also been applied to microcavities [46]. The same group also demonstrated three-dimensional DBRs with micrometer resolution [47].…”

“…The technique of focused ion beam has led to several reports showing the patterning of PSi PL (Section 14.4.3.1.1) [44] and photonic structures (Section 14.4.2.2.2) [45][46][47].…”

Fabrication of porous silicon based tunable distributed Bragg reflectors by anodic etching of irradiated silicon

“…Hence the optical thickness after irradiation should be (nd) 0 < (nd). This effectively means that the DBR structures prepared by irradiated samples can reflect smaller wavelength, since nd ¼ k 4 [4]. Hence the observed changes in the stop band and central wavelengths can be attributed to the effects caused by irradiation.…”

“…Ion/gamma irradiation and subsequent anodization of silicon can be a very efficient method to fabricate tunable distributed Bragg reflectors without changing the layer parameters [4,18]. In particular, by ion irradiation one can achieve spatial selectivity and accuracy that could be used to change the structural and optical properties of the material [19,20].…”

“…Porous silicon (pSi) has been investigated extensively as a possible candidate for developing waveguides, light emitting diodes and distributed Bragg reflectors (DBR) etc. [1][2][3][4][5]. There are various methods to synthesize porous silicon (pSi), particularly electrochemical etching is a relatively easy and convenient method to prepare homogeneous nanostructured layers [6].…”