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ACS Appl Mater Interfaces. 2017 May 24;9(20):17526-17535. doi: 10.1021/acsami.7b00099. Epub 2017 May 15.

Al2O3 Passivation Effect in HfO2·Al2O3 Laminate Structures Grown on InP Substrates.

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Institute of Physics and Applied Physics, Yonsei University , Seoul 120-749, Korea.
Center of Opto-Electronic Materials, Korea Institute of Science and Technology , Seoul 136-791, Korea.
Department of Material Science and Engineering, Sungkyunkwan University , Suwon 440-746, Korea.


The passivation effect of an Al2O3 layer on the electrical properties was investigated in HfO2-Al2O3 laminate structures grown on indium phosphide (InP) substrate by atomic-layer deposition. The chemical state obtained using high-resolution X-ray photoelectron spectroscopy showed that interfacial reactions were dependent on the presence of the Al2O3 passivation layer and its sequence in the HfO2-Al2O3 laminate structures. Because of the interfacial reaction, the Al2O3/HfO2/Al2O3 structure showed the best electrical characteristics. The top Al2O3 layer suppressed the interdiffusion of oxidizing species into the HfO2 films, whereas the bottom Al2O3 layer blocked the outdiffusion of In and P atoms. As a result, the formation of In-O bonds was more effectively suppressed in the Al2O3/HfO2/Al2O3/InP structure than that in the HfO2-on-InP system. Moreover, conductance data revealed that the Al2O3 layer on InP reduces the midgap traps to 2.6 × 1012 eV-1 cm-2 (compared to that of HfO2/InP, that is, 5.4 × 1012 eV-1 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.


Al2O3 passivation layer; HfO2 laminate structure; defect states; indium phosphide; interfacial reaction


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