Undoped Strained Ge Quantum Well with Ultrahigh Mobility of Two Million

Zhenzhen Kong; Zonghu Li; Gang Cao; Jiale Su; Yiwen Zhang; Jinbiao Liu; Jingxiong Liu; Yuhui Ren; Huihui Li; Laiming Wei; Guo-Ping Guo; Yuanyuan Wu; Henry H Radamson; Junfeng Li; Zhenhua Wu; Hai-Ou Li; Jiecheng Yang; Chao Zhao; Tianchun Ye; Guilei Wang

doi:10.1021/acsami.3c03294

Undoped Strained Ge Quantum Well with Ultrahigh Mobility of Two Million

ACS Appl Mater Interfaces. 2023 Jun 14;15(23):28799-28805. doi: 10.1021/acsami.3c03294. Epub 2023 May 11.

Authors

Zhenzhen Kong^{1

2}, Zonghu Li³, Gang Cao^{3

4

5}, Jiale Su¹, Yiwen Zhang^{1

2}, Jinbiao Liu^{1

2}, Jingxiong Liu^{1

2}, Yuhui Ren^{1

2}, Huihui Li⁶, Laiming Wei⁷, Guo-Ping Guo^{3

4

5}, Yuanyuan Wu⁸, Henry H Radamson⁸, Junfeng Li¹, Zhenhua Wu^{1

2}, Hai-Ou Li^{3

4

5}, Jiecheng Yang³, Chao Zhao⁶, Tianchun Ye^{1

2}, Guilei Wang^{1

4

6}

Affiliations

¹ Integrated Circuit Advanced Process R&D Center, Institute of Microelectronics, Chinese Academy of Sciences, Beijing 100029, P. R. China.
² School of Integrated Circuits, University of Chinese Academy of Sciences, Beijing 100049, P. R. China.
³ CAS Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei 230026, P. R. China.
⁴ Hefei National Laboratory, Hefei 230088, P. R. China.
⁵ Origin Quantum Computing Company Limited, Hefei 230026, P. R. China.
⁶ Beijing Superstring Academy of Memory Technology, Beijing 100176, P. R. China.
⁷ School of Advanced Manufacturing Engineering, Hefei University, Hefei 230601, P. R. China.
⁸ Research and Development Center of Optoelectronic Hybrid IC, Guangdong Greater Bay Area Institute of Integrated Circuit and System, Guangzhou 510535, P. R. China.

PMID: 37166277
DOI: 10.1021/acsami.3c03294

Abstract

We develop a method to fabricate an undoped Ge quantum well (QW) under a 32 nm relaxed Si_0.2Ge_0.8 shallow barrier. The bottom barrier contains Si_0.2Ge_0.8 (650 °C) and Si_0.1Ge_0.9 (800 °C) such that variation of Ge content forms a sharp interface that can suppress the threading dislocation density (TDD) penetrating into the undoped Ge quantum well. The SiGe barrier introduces enough in-plane parallel strain (ε_∥ strain -0.41%) in the Ge quantum well. The heterostructure field-effect transistors with a shallow buried channel obtain an ultrahigh two-dimensional hole gas (2DHG) mobility over 2 × 10⁶ cm²/(V s) and a very low percolation density of (5.689 ± 0.062) × 10¹⁰ cm^-2. The fractional indication is also observed at high density and high magnetic fields. This strained germanium as a noise mitigation material provides a platform for integration of quantum computation with a long coherence time and fast all-electrical manipulation.

Keywords: 2DHG; RPCVD; compression strain; mobility; quantum computing; undoped Ge/SiGe heterostructure.