Investigations of the Anodic Porous Etching of n-InP in HCl by Atomic Absorption and X-ray Photoelectron Spectroscopies

Abstract

The electrochemical porous etching of n-InP in 1 M HCl has been investigated by monitoring the mass of In 3+ released during and after the anodic polarization. The study has been performed on both crystal-oriented (CO) and current line-oriented (CLO) pores grown at 10 mA·cm −2 and 5 V vs Ag/AgCl. An unexpected evolution of the mass of In 3+ has been measured when the electrochemical dissolution process is stopped. It indicates a mass loss more than twice higher after 2 or 3 hours. This demonstrates that the accurate amount of dissolved InP must be considered a longtime after the end of the polarization. The comparisons of the etched masses for CO and CLO pores with the values calculated from the coulometric charges indicate that the etching processes are similar for the two pore geometries and that the dissolution valence for InP is 2. The chemical analyses, performed by X-ray photoelectron spectroscopy, reveal that the main corrosion products are Cl-containing compounds such as InCl 3 . This gives valuable information to confirm an InP porous etching mechanism proposed earlier in literature. Likewise other one-dimensional nanostructures, electrochemically grown porous semiconductors have become an attractive field of interest. Though numerous attempts to understand the pore formation have been carried out, crucial mechanistic parameters such as the dissolution valence (z) are still not clarified for III-V compounds since most of the studies refer to the porous etching of Si.1 Gravimetric investigations have pointed out different z during electropolishing and pore formation on Si.2 The dissolution valence is 4 (the expected value since Si is a tetravalent element) during electropolishing and it does not depend on the applied current density ( j), the doping or the electrolyte concentration (c). Conversely, z varies, from 2 to 4, with those parameters during porous etching. Furthermore, the dissolution valence during the pore growth can be 4 at the tips and 2 on the walls. 3 It illustrates that porous dissolution process is a tricky phenomenon and it is different from uniform polishing.The pore growth mechanisms reported in literature can be divided in two families: "chemical" and "physical" models. The latter are based on the charge carrier distribution at the semiconductor/electrolyte interface and can basically be applied to any semiconductor since no chemical aspects are considered. However strong differences are observed between Si, which is an elemental semiconductor, and III-V compounds or between III-V materials themselves. 4 Thus chemical aspects must also be considered to depict accurately the porous dissolution of such materials. The peculiar dissolution along 111 B directions leading to crystal-oriented (CO) pores in GaP, GaAs and InP (with B referring to the second element for A-B compounds, e. g. P in InP and GaP) [5][6][7] or the catacomb-like pore morphology observed solely on GaP 8 emphasizes the influence of the chemical nature of the semiconductors on the pore growth. The chemical aspect of the...

Photoanodic oxidation of InP in acid solution and its surface chemistry: On the interplay of photons, protons and hydrodynamics

“…Fundamental studies of anodic oxidation of InP are fewer [22][23][24] . The electrochemical approach has been used successfully for (nano)porous etching of InP [25][26][27][28][29] and for studies of oxide growth [30][31][32][33][34] . In this paper we describe the results of a study of photoanodic oxidation and dissolution of n-type InP and, for comparison, n-type GaAs in H 2 SO 4 and HCl solution.…”

Selective Detection of H2 Gas in Gas Mixtures Using NiO‐Shelled Pd‐Decorated ZnO Nanowires

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A short review of the electrochemical technologies for pit arrays fabricated on the surfaces of indium phosphide wafer

“…Santinacci Lionel et al [ 49 ] assembled porous layers on the surfaces of a n -InP slice in a HCl solution stirred by nitrogen gas. The whole experimental set-up was illustrated in Fig.…”

“…However, there are few specific reviews on electrochemical etching experimental devices and methods for InP. Therefore, in this paper, twelve electrochemical methods for fabricating hole arrays on the surface of InP wafers were introduced, and the structure and experimental process of the electrochemical set-up were highlighted [ 32 , [42] , [43] , [44] , [46] , [47] , [48] , [49] , [50] , [51] ]. It provided a useful reference guide for the large-scale assembly of regular hole arrays on the surface of InP sheets.…”