Reduced interface state density after photocurrent oscillations and electrochemical hydrogenation of n-Si(111): A surface photovoltage investigation

Abstract

The electrochemical H-termination process of n-Si(111) surfaces in aqueous 0.1 M NH4F pH 4.0 solution was optimized for a two step procedure consisting of the surface smoothing during oxidation in the photocurrent oscillating potential region followed by the oxide etching and passivation of the surface atoms with hydrogen. The hydrogen termination was monitored in situ measuring the dark current transient and evaluated using pulsed surface photovoltage technique. An unusually low density of interface states it=1×1010 eV−1 cm−2 was obtained by the hydrogen termination on n-Si(111) surfaces following this procedure with better results than applying an electropolishing treatment.

Surface photovoltage phenomena: theory, experiment, and applications

“…For example, the analysis based on Eq. (5.34) has been applied to the study of HF and H 2 O treated Si(111) surfaces [717,718], Si(111)/lead-boro-alumino-silicate glass [713] and Si/porous Si [719], and mostly chemically [720±725] and electrochemically [714,726,727] Hterminated Si (111) surfaces. The same approach was used by Venger et al to study the surface state distribution at real Ge [568] and GaAs [569] surfaces.…”

Electrochemical Passivation and Modification of c-Si surfaces

“…Still, the interface defect density of such surfaces is similar or below that of a flat Si(111) surface shown in Fig. 4.10b [11,15]. Additionally, this type of surface structure explains the fast decay of I PL after the H-termination process due to 3D-etching of the small hillocks.…”

“…The amount of defects on the Hterminated surface is reduced by a factor of about 10 with respect to the Htermination after oxidation at +3 V as calculated from ~. This behaviour leads to an unexpected low defect concentration of about 10 10 cm -2 on this Si(100) surface [15] which is typically observed on Si(111) surfaces only [11]. Additionally, at +3 V (during oxidation) of the Si(111) interface is about half of the value as measured for the other surface orientations at the same oxidation potential (see Fig.…”

“…Oxide layers and even organically modified surfaces can be prepared anodically in aqueous and non-aqueous solutions. At certain conditions, electropolishing of Si surfaces [8][9][10] can be performed leading to Si surfaces with extraordinary electronic properties [11] despite of the undulated surface morphology.…”

Tailoring of Interfaces for the Photoelectrochemical Conversion of Solar Energy

“…Under these conditions, the Si -oxide interface will exhibit an increased roughness because the system is characterized by the simultaneous existence of various p i ( t ) (e.g., i − N , … , i − 1, i ). Indeed, such oscillatory phenomena have been used for the preparation of electronically superior Si single -crystal surfaces [236] , because the oscillatory behavior is a macroscopic phenomenon and hence synchronization occurs throughout the sample surface. Any structure formed in this process exists on the overall sample surface resulting in the scalability of the related nanostructures which can be used for the preparation of solar energy converting devices (see Sections 2.5 and 2.6 ).…”