Photoluminescence and AFM characterisation of photochemically etched highly resistive n‐type silicon

Abstract

A light-emitting layer has been made on highly resistive n-type silicon (6.4 kΩcm) using photochemical etching in a mixture of HF with H 2 O 2 . The morphology of the porous films grown after exposure to a HeNe laser (633 nm) at normal incidence was analysed by Atomic Force Microscopy (AFM). The results show that the film obtained are porous and the morphology of the porous layer obtained are shown to be similar to that obtained by the electrochemical method on highly doped silicon. Furthermore, excitation of the porous silicon layer formed on highly resistive silicon samples under He-Cd laser (325 nm) irradiation shows that the PL intensity increases with increasing etching time. The maximum PL spectrum peaked at 636 nm with a FWHM of about 0.3 eV. Finally, the quantum confinement effect has been invoked to explain the bright, visible, room temperature PL of porous silicon (PS).

Properties of light-emitting porous silicon photoetched in aqueous HF∕FeCl3 solution

“…It is considered that the essentially same mechanism may occur during porous layer formation in photoetching as in stain etching. 22 The PL intensity is also found to be roughly proportional to the PSi film thickness ͓cf. Figs.…”

Properties of Pt-Assisted Electroless Etched Silicon in HF/Na₂S₂O₈ Solution

“…These results allow concluding that the shape of the pores depends on the type of etching solution and the etching rate is controlled by the type of the deposited metal. In our previous work, we have observed the morphology of etched layer (pores shape) changes when Na 2 S 2 O 8 is replaced by another type of oxidizing agent (KMnO 4 or K 2 Cr 2 O 7 ), which means that the morphology strongly depends on the type of oxidizing agent [7][8][9][10]. This is corroborated by the fact that the morphology does not change significantly when the concentration of Na 2 S 2 O 8 increases (Fig.…”