通过SiGe层组分工程增强Ge量子阱异质结构的电荷稳定性

中文摘要 AI 辅助

组分调制是一种设计具有定制性能材料的强大技术，推动了先进半导体器件的发展。在本工作中，我们将这一技术应用于Ge量子阱异质结构，为解决自旋量子比特器件中电荷稳定性的关键挑战提供了一条有前景的途径。利用分子束外延的原子级精度，我们通过梯度组分调制设计了SiGe顶层势垒的能带结构，从而减少了SiGe-介质界面的电荷积累态，并增强了对Ge量子阱中空穴气体的有效限制。组分调制的SiGe/Ge量子阱异质结构增强的电荷稳定性在霍尔器件中得到了证实，表现为稳定的栅极电压范围扩大。我们进一步从组分调制的SiGe/Ge量子阱异质结构制备了量子点器件，并观察到极低的电荷噪声，在1 Hz时平均幅度为$0.46\\,\mathrm{\mu eV}/\mathrm{\sqrt{Hz}}$——这是硅上生长的Ge量子阱所报道的最低值。这种量子点卓越的电荷稳定性在少空穴区域持续存在，在约数小时内没有可观察到的电压漂移。凭借降低的电荷噪声和增强的能量稳定性，组分调制的SiGe/Ge异质结构在构建高性能量子器件（包括具有长相干时间的自旋量子比特）方面展现出巨大的应用潜力。

英文摘要

Composition modulation is a powerful technique for designing materials with tailored properties, fueling the development of advanced semiconductor devices. In this work, we have implemented this technique into Ge quantum well heterostructures, offering a promising avenue to address the critical challenge of charge stability in spin qubit devices. Harnessing the atomic-scale precision of molecular beam epitaxy, we have engineered the band structure of the SiGe top barrier via graded composition modulation, thereby reducing charge accumulation states at the SiGe-dielectric interface and strengthening the effective confinement to the hole gases in the Ge quantum wells. The enhanced charge stability of composition-modulated SiGe/Ge quantum well heterostructures is confirmed in Hall devices, featuring an enlarged stable gate voltage range. We have further fabricated quantum dot devices from the composition-modulated SiGe/Ge quantum well heterostructures and observed remarkably low charge noise with an averaged amplitude of $0.46\,\mathrm{μeV}/\mathrm{\sqrt{Hz}}$ at $1\,\mathrm{Hz}$---the lowest reported value for Ge quantum wells grown on silicon. This exceptional charge stability of the quantum dots persists in the few-hole regime, with no observable voltage drift over $\sim$hours. With reduced charge noise and enhanced energy stability, composition-modulated SiGe/Ge heterostructures exhibit significant potential for applications in building high-performance quantum devices, including spin qubits with a long coherence time.

发表机构

• Beijing Academy of Quantum Information Sciences（北京量子信息科学研究院）

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