Defect Analysis And Performance Evaluation Of P-type Epitaxial GaAs Layer On Ge Substrate For GaAs/Ge Based Advanced Device

Goutam Kumar Dalapati1*, Vignesh Suresh1, Sandipan Chakraborty2, Chandreswar Mahata3, Yi Ren1, Thirumaleshawara Bhat1, Sudhiranjan Tripathy1, Taeyoon Lee3, Lakshmi Kanta Bera1, Dongzhi Chi1

1Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), Fusionopolis Way, #08-03, Innovis 138634, Singapore

2Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive, 3, 117576, Singapore

3Nanobio Device Laboratory, School of Electrical and Electronic Engineering, Yonsei University,134 Shinchon-Dong, Seodaemun-Gu, Seoul 120-749, Republic of Korea

Adv. Mater. Lett., 2016, 7 (7), pp 517-524

DOI: 10.5185/amlett.2016.6439

Publication Date (Web): Jun 12, 2016

E-mail: dalapatig@imre.a-star.edu.sg

Abstract


The structural defects and formation of native oxides during thermal treatment on p-type epitaxial-GaAs/Ge have been investigated using spectroscopic measurements and electrical characterization. The performance of epi-GaAs based device depends on the interface quality between epi-GaAs and gate oxide and structural quality of the epi-GaAs layer. P-type epitaxial-GaAs was grown on Ge substrate using MOCVD technique at 675oC. Defective surface native oxides of arsenic and gallium oxides are observed for as-grown epi-GaAs layer. The arsenic oxide significantly reduced after thermal treatment as seen from XPS observations. The structural defects at surface enhanced after thermal treatment which is clearly probed by micro-Raman spectroscopy. Atomic layer deposited (ALD) Al2O3 significantly improved the interface properties after thermal treatment compared with bare epi-GaAs layer. Even though, the interface trap defect density slightly higher for p-type epi-GaAs MOS capacitor compared with bulk p-type GaAs devices, high frequency-dispersion in epi-GaAs based devices observed. This is mainly governs through the formation of p-i-n junction diode in the epi-GaAs layer on Ge substrates.

Keywords

GaAs, native oxides, Raman spectroscopy, rapid thermal annealing, GaAs/Ge integration.

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