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AlO passivation effect in HfO·AlO laminate structures grown on InP substrates Hang-Kyu Kang, Yu-Seon Kang, Dae-Kyoung Kim, Min Baik, Jin Dong Song, Youngseo An, Hyoungsub Kim, and Mann-Ho Cho ACS Appl. Mater. Interfaces, Just Accepted Manuscript • DOI: 10.1021/acsami.7b00099 • Publication Date (Web): 07 Apr 2017 Downloaded from http://pubs.acs.org on April 9, 2017
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ACS Applied Materials & Interfaces
Al2O3 passivation effect in HfO2·Al2O3 laminate structures grown on InP substrates
Hang-Kyu Kang1,2, Yu-Seon Kang1,, Dae-Kyoung Kim1, Min Baik1, Jin-Dong Song2, Youngseo An3, Hyoungsub Kim3, Mann–Ho Cho1,*
1
2Center
Institute of Physics and Applied Physics, Yonsei University, Seoul, 120-749, Korea
of Opto-Electronic Materials, Korea Institute of Science and Technology, Seoul 136-791, Korea
3Department
of Material Science and Engineering, Sungkyunkwan University, Suwon 440-746, Korea
KEYWORDS: Al2O3 passivation layer, indium phosphide, HfO2 laminate structure, Interfacial reaction, Defect states.
ABSTRACT The passivation effect of an Al2O3 layer on electrical properties were investigated in HfO2-Al2O3 laminate structures grown on InP substrate by atomic layer deposition. The chemical state using HR-XPS showed that interfacial reactions were dependent on the presence of the Al2O3 passivation layer and its sequence in the HfO2-Al2O3 laminate structures. The Al2O3/HfO2/Al2O3 structure showed the best electrical characteristics, due to the interfacial reaction, compared with those of different stacking structures. The top Al2O3 layer suppressed the interdiffusion of oxidizing species into the HfO2 films, while the bottom Al2O3 layer blocked the outdiffusion of In and P atoms. As a result, the formation of In-O bonds was effectively suppressed in the Al2O3/HfO2/Al2O3/InP structure than that of HfO2-on-InP system. Moreover, conductance data revealed that the Al2O3 layer on InP reduces the midgap traps to 2.6 10 eV
cm-2 (compared with that of HfO2/InP = 5.4 10 eV
cm-2). The suppression of gap
states caused by the outdiffusion of In atoms significantly controls the degradation of capacitors caused by leakage current through the stacked oxide layers.
* Electronic mail:
[email protected] 1 ACS Paragon Plus Environment
ACS Applied Materials & Interfaces
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I. INTRODUCTION The scaling of Si-based metal-oxide-semiconductor (MOS) devices with regard to the global trend toward high speed and low power consumption is currently reaching its fundamental limits.1–2 The downscaling of SiO2 has reached its physical limits owing to critical issues associated with poor reliability, high frequency dispersion, and high leakage current.3 To overcome such problems, a III-V-based MOS system combined with a high-κ oxide have been widely studied.1–3 In particular, indium phosphide (InP) is of interest owing to its high mobility (approximately four times that of Si) and high breakdown endurance. Moreover, recent studies related to electrical properties in high-κ oxides/InP showed that n-channel MOS field effect transistors (MOSFETs) on InP substrates have excellent electrical performance including large transconductance, large drain current, and low leakage current.2–4 High-κ oxides such as HfO2, HfSi O , and HfSiO N are commonly used for MOSFETs that have InP channels.4 However, thermal instability caused by the diffusion of substrate elements into the high-κ films, as well as poor interface quality, critically affect the instability and degradation of the device performance. In recent years, atomic-layer-deposited (ALD) aluminum oxide (Al2O3) thin films have been investigated as a candidate for surface passivation materials because the interfacial diffusion from the substrate to the high-κ film can be effectively suppressed by the ALD Al2O3.5 Moreover, ALD-Al2O3 thin films can effectively passivate the semiconductor surface even at a low growth temperature (
