Digital Electrochemical Etching of Compound Semiconductors

1991 ◽  
Vol 237 ◽  
Author(s):  
Q. Paula Lei ◽  
John L. Stickney
Keyword(s):  
Electrochemical Cell ◽  
Electrochemical Etching ◽  
Compound Semiconductors ◽  
Atomic Layer ◽  
Atomic Level ◽  
Level Control ◽  
Square Wave ◽  
Etching Method ◽  
Cdte Substrate ◽  
Initial Results

AbstractThe principles for an electrochemical digital etching method for compound semiconductors are described and initial results reported. The method is designed to allow atomic level control over the etching process, resulting in the removal of a bilayer of the compound for each cycle. An atomic layer of one element is removed at one potential and then an atomic layer of the second element is removed at a second potential to complete one cycle. The results reported here are for the etching of CdTe. For CdTe, Te is stripped by reduction to Te2- while Cd is stripped by oxidation to Cd2+. Underpotentials are chosen so that only the top atomic layer of an element is removed. Potentials sufficient to strip the elemėnt from the bulk of the CdTe substrate are avoided. Application of the method should involve the use of a simple electrochemical cell, with solution convection. The substrate is placed in the cell and a square wave applied, where each cycle results in the dissolution of a bilayer of the compound. The two potentials of the square wave correspond to underpotential stripping potentials for Cd and Te respectively. Directions for the future development of this etching method are discussed.

Formation of CdTe and GaAs by Electrochemical Atomic Layer Epitaxy (ECALE)

1991 ◽  
Vol 222 ◽  
Author(s):  
D. Wayne Suggs ◽  
Ignacio Villegas ◽  
Brian W. Gregory ◽  
John L. Stickney
Keyword(s):  
Surface Analysis ◽  
Electrochemical Cell ◽  
Compound Semiconductors ◽  
Atomic Layer ◽  
Atomic Layer Epitaxy ◽  
Electrochemical Technique ◽  
Analysis Instrument ◽  
Electrochemical Atomic Layer Epitaxy ◽  
Analysis Environment

ABSTRACTThe principles of Atomic Layer Epitaxy (ALE) have been applied to the formation of compound semiconductors by an electrochemical technique, referred to as Electrochemical Atomic Layer Epitaxy (ECALE). Atomic layers of the component elements are alternately electrodeposited at underpotential (UPD) from separate solutions and at separate potentials. Results are presented concerning the structures of both CdTe and GaAs deposits formed by ECALE. Studies were performed using singlecrystalline Au electrodes in a UHV surface analysis instrument coupled directly with an electrochemical cell. This instrument was used in order to prevent corruption by contact with air during transfer to the surface analysis environment.

Atomic level control of pattern fidelity during SAC etch

2021 ◽  
Author(s):  
Mingmei Wang ◽  
Du Zhang ◽  
Shinya Morikita ◽  
Yanxiang Shi ◽  
Hojin Kim ◽  
...  
Keyword(s):  
Atomic Level ◽  
Level Control

FABRICATION OF STM TUNGSTEN NANOTIP BY ELECTROCHEMICAL ETCHING METHOD

2009 ◽  
Vol 08 (03) ◽  
pp. 305-310 ◽  
Author(s):  
GHODRAT TAHMASEBIPOUR ◽  
VAHID AHMADI ◽  
AMIR ABDULLAH ◽  
YOUSEF HOJJAT
Keyword(s):  
Mechanical Strength ◽  
Tungsten Wire ◽  
Electrochemical Etching ◽  
Sample Surface ◽  
Scanning Tunneling ◽  
Etching Method ◽  
First Choice ◽  
Stm Tips ◽  
Set Up ◽  
Tungsten Tip

With developments in nanoscience and nanotechnology, Scanning Tunneling Microscope (STM) has found a wide application in imaging the atoms, molecules, and nanostructures. This microscope uses an ultra sharp metallic tip for scanning sample surface to produce surface topographic image with atomic resolution. Reliability and resolution of STM images depend largely on the sharpness of the tip apex and repeatability of images depends on mechanical strength of tip material. During last decades, a variety of techniques and processes have been developed for fabrication of different metallic tips made from tungsten, platinum, platinum–iridium, gold, and silver. Electrochemical etching process is the most popular method for fabrication of nanotips with desired quality, reliability, and reproducibility and tungsten is normally the first choice for fabrication of STM tips as it has a high mechanical strength as well as a good electrical conductivity. Fabrication of STM tungsten tip by using electrochemical etching method and tip characterization has been the subject of several researches. Nevertheless, to our knowledge, effect of voltage type (AC/DC), time delay in turning off the voltage, tungsten wire diameter, environmental vibrations, electrolyte type, cathode material, and perpendicularity of tungsten wire (toward electrolyte surface) on the tip sharpness have not been studied so far. In this paper, effects of these parameters on the tip shape and sharpness are investigated. A proper set-up for STM tungsten nanotip fabrication by using electrochemical etching method is presented.

Atomic-Level Studies of Processes on Metal Surfaces

MRS Bulletin ◽  
1994 ◽  
Vol 19 (7) ◽  
pp. 35-40
Author(s):  
G.L. Kellogg ◽  
T.T. Tsong
Keyword(s):  
Solid Surface ◽  
Chemical Vapor ◽  
Atomic Layer ◽  
Atom Probe ◽  
Atomic Level ◽  
Crystalline Solid ◽  
Complex Materials ◽  
Fundamental Insight ◽  
Analytical Tools ◽  
Field Ion Microscope

An atomic-level understanding of surface phenomena is becoming increasingly important as materials scientists and engineers begin to fabricate new materials by controlling their growth at the nanometer or subnanometer scale. Recent advances in molecular beam epitaxy and chemical vapor deposition make it possible to assemble a crystalline solid or epitaxial overlayer literally one atomic layer at a time. The need to characterize the structure and composition of these complex materials in finer and finer detail has forced the traditional analytical tools (e.g., electron microscopy) to strive for better and better spatial resolution. It has also generated a virtual explosion in the proliferation of scanning probe microscopies inherently capable of viewing surface structure at the atomic level. This same need has recently rekindled an interest in the technique that first allowed scientists to view a solid surface in atomic detail: the field ion microscope (FIM). The unique attributes of this instrument and its successor, the atom probe mass spectrometer, make it possible to observe individual atoms on a solid surface, to remove atoms from the surface one atomic layer at a time, and to determine the chemical identity of the atoms as they are removed. The close match between these capabilities and the requirements of modern-day materials analysis have stimulated renewed efforts to use the FIM to gain fundamental insight into materials problems. This article discusses a few selected applications of the FIM, individually and combined with the atom probe, to phenomena occurring at the surface of solid materials.

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