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Oxidation and etching behaviors of the InAs surface in various acidic and basic chemical solutions
Na, Jihoon,Lee, Seunghyo,Lim, Sangwoo Elsevier 2017 Surface science Vol.658 No.-
<P><B>Abstract</B></P> <P>Indium arsenide (InAs) is the candidate of choice as a new channel material for application in future technologies beyond the Si–based electronic devices because it has a much higher electron mobility than silicon. In this study, the oxidation and etching behaviors of InAs (100) in various acidic and basic solutions, such as HF, HCl, H<SUB>2</SUB>SO<SUB>4</SUB>, NaOH, KOH, and NH<SUB>4</SUB>OH, were investigated. In addition, the effect of pH on the oxidation and etching reactions taking place on the InAs surface was studied using solutions with a pH ranging from 1 to 13. It was observed that the oxidation of the InAs surface was hindered in acidic solutions, which was attributed to the dissolution of the oxidized surface layer. In particular, the treatment of the InAs surface using a strongly acidic solution with a pH of less than 3 produced an oxide–free surface due to the predominant etching of the InAs surface. The addition of H<SUB>2</SUB>O<SUB>2</SUB> to the acidic solutions greatly increased the etching rate of the InAs surface, which suggests that the oxidation process is the rate–limiting step in the sequence of reactions that occur during the etching of the InAs surface in acidic solutions. The etching of InAs was suppressed in neutral solutions, which resulted in the formation of a relatively thicker oxide layer on the surface, and mild etching of the InAs surface took place in basic solutions. However, in basic solutions, the addition of H<SUB>2</SUB>O<SUB>2</SUB> did not significantly contribute to the increase of the oxidation state of the InAs surface; thus, its effect on the etching rate of InAs was smaller than in acidic solutions.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Oxidation and etching behaviors of InAs was investigated in acidic and basic solutions. </LI> <LI> Oxide-free InAs surface could be prepared at the pH lower than 4. </LI> <LI> In the strong bases, relatively thin InAs oxide layer was present due to a mild etching. </LI> <LI> Oxidation of InAs is a rate limiting step in the overall etching process in strong acids. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Elemental behaviors of InGaAs surface after treatment in aqueous solutions
Na, Jihoon,Lim, Sangwoo Elsevier 2019 MICROELECTRONIC ENGINEERING Vol.212 No.-
<P><B>Abstract</B></P> <P>Indium gallium arsenide (InGaAs) is one of the candidates as a channel material for the high-performance complementary metal-oxide-semiconductor (CMOS) devices superior to silicon-based CMOS devices because of its higher electron mobility. In order to introduce InGaAs as a new channel material for high-performance CMOS devices, it is important to prepare its surface to suppress material loss and surface oxide formation in the InGaAs layer. In this study, the behavior of each element of the In<SUB>0.53</SUB>Ga<SUB>0.47</SUB>As surface in chemical solutions such as HCl, NH<SUB>4</SUB>OH, HPM (HCl/H<SUB>2</SUB>O<SUB>2</SUB>/H<SUB>2</SUB>O) and APM (NH<SUB>4</SUB>OH/H<SUB>2</SUB>O<SUB>2</SUB>/H<SUB>2</SUB>O) was investigated from the viewpoint of thermodynamics and reaction kinetics. In the acidic HCl solution, the dissolution of the InGaAs surface was the dominant reaction, whereas a sub-oxide formed on the InGaAs surface in the basic NH<SUB>4</SUB>OH solution. The formation of the oxide on the surface was considered the rate-limiting step of the overall etching reaction of InGaAs in the acidic solution; therefore, the surface oxidation and overall etching (dissolution) of the InGaAs layer were determined using different amounts of H<SUB>2</SUB>O<SUB>2</SUB> in the solution. In particular, the overall etching of the InGaAs surface in the HPM solution was more aggressive than that in the APM solution. The behavior of InGaAs in the surface preparation process sequences with APM, HPM, and HF was also investigated, and it was observed that the material loss and surface roughening of the InGaAs layer were mostly determined in the HPM process. Finally, it was possible to suppress the surface oxidation, material loss, and surface roughening of the InGaAs layer by reducing the concentration of H<SUB>2</SUB>O<SUB>2</SUB> in the HPM solution.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Oxide formation on InGaAs surface is a rate limiting step in overall etching process in HPM (HCl/H<SUB>2</SUB>O<SUB>2</SUB>/H<SUB>2</SUB>O). </LI> <LI> Dissolution of the oxide is a rate-limiting step in APM (NH<SUB>4</SUB>OH/H<SUB>2</SUB>O<SUB>2</SUB>/H<SUB>2</SUB>O) solution. </LI> <LI> HPM process mostly determines oxide formation and material loss. </LI> <LI> H<SUB>2</SUB>O<SUB>2</SUB> concentration in HPM solution is a key factor to control surface behavior. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Na, Jihoon,Choi, Hae Young,Choi, Eun Seo,Lee, ChangSu,Lee, Byeong Ha The Optical Society 2009 Applied Optics Vol.48 No.13
<P>We present a method for simultaneously measuring the thickness and the group refractive index of a specimen using self-referenced spectral-domain fiber-based interferometry. By removing the scanning part and using the fiber-based configuration, the system complexity and stability could be significantly improved. To minimize the system drift, we utilized the signals originated from the fiber ends of both arms. Implementing in a self-referenced configuration, we could improve the measurement accuracy down to a decimal place. Experimental measurements were made with a 1.555 mm thick fused silica plate. At 814 nm the thickness was measured as 1.5546 +/- 0.0002 mm, and at the same time, the group index was obtained as 1.4627 +/- 0.0002.</P>
Thickness and Refractive Index Measurements by Full-Field Optical Coherence Microscopy
Jihoon Na,Choi, W.J.,Hae Young Choi,Seon Young Ryu,Eun Seo Choi,Byeong Ha Lee IEEE 2009 IEEE SENSORS JOURNAL Vol.9 No.12
<P>We present the noble sensing method that can simultaneously measure the physical thickness and the refractive index of a transparent specimen based on full-field optical coherence microscopy. As a sample, a small drop of epoxy was placed on a flat glass plate and high-resolution depth resolved en-face images were taken. With adopting the reference plane from a cross-sectional image, the physical thickness, and the refractive index distribution could be obtained.</P>