Functionalization and characterization of InAs and InP surfaces with hemin

Abstract

Chemical functionalization of hemin molecules onto InAs and InP is reported. X-ray photoelectron spectroscopy (XPS), atomic force microscopy, and spectroscopic ellipsometry (SE) analyses are used to characterize the III-V surfaces. One notable feature of the C 1s core level spectra is a peak at ∼284eV observed for the functionalization chemistries, which is attributed to CN bonding within the porphyrin molecule. This is corroborated by the observation of N 1s, Fe 2p, and other distinguishable chemical bonding peaks. For example, in the As 3d and P 2p core levels, –COOH bonding is observed to the As and P anion in the InAs and InP samples, respectively, which implies chemisorption of the functional groups to the material surfaces. Another result of the XPS analysis is the impact of the surface functional group on the electronic state of the surface causing upward band bending of the valence band maximum, indicating surface charge transfer as explored in previous work [Garcia et al., Appl. Phys. Lett. 88, 013506 (2006)]. SE analysis on the functionalization process provides data for the effect of hemin and benzoic acid solution concentrations. The authors discuss the dependence of the band bending, surface coverage, and hemin layer thickness as determined by XPS and SE.

Quantum interference measurement of spin interactions in a bio-organic/semiconductor device structure

“…Surface characterization of hemin-functionalized InAs for NO sensing 13 and surface studies of PP-IX on Pt vs ZnPP-IX on Pt 25 suggest that PP-IX and hemin anchor to a metallic surface through the carboxylic groups, predominantly in an upright orientation for PP-IX, although for ZnPP-IX, the molecules were at an angle from the normal to the surface. Several interactions are at play, including chemisorption via the carboxylic groups, π-interaction between protoporphyrins, and electrostatic interaction between the metal ion of the hemin and the 2DES.…”

“…Hemin-functionalized InAs and InP surfaces e.g. act as sensitive sensors for NO 13 . The electronic structure of iron in hemoglobin and hemin in solution indicate a high-spin ferric state 14 .…”

Surface states mediated charge transfer in redox behavior of hemin at GaAs(100) electrodes

“…$À0.06 V vs. SCE. 39 Surface states localized within the semiconductor bandgap, originating either in defects or adsorbed species, may be, however, as well involved in the charge exchange being able to mediate electron transfer. 36,[40][41][42][43] Electron transfer occurs, in this case, through population of such levels by either the conduction band in n-type or valence band in p-type semiconductor, yielding different currents for n-and p-GaAs since the concentrations of electrons and holes are dopant dependent.…”

Optical and Electronic NOx Sensors for Applications in Mechatronics

“…Herein, we present an overview of surface chemistry and sensor function results for hemin functionalized surfaces and its response to NO. The approach we devised for obtaining electrical data for NO gas detection is based on the established four-contact van der Pauw (VDP) method for characterizing sheet resistivity [ 47 , 48 ]. This methodology differs from current chemical sensors in a variety of ways.…”