Realization of smooth side profile using diffusion-controlled wet chemical etching for HgTe/(Hg,Cd)Te heterostructures

Shekhar, Pragya; Bendias, Kalle; Fürst, Lena; Liang, Xiaobo; Gbordzoe, Michael; Borzenko, Tatiana; Buhmann, H.; Kleinlein, Johannes; Molenkamp, Laurens W.

doi:10.1088/1361-6528/acba1d

Cited by 2 publications

(2 citation statements)

References 28 publications

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“…As a first step of the device fabrication process, we pattern the Hall bar mesa structure (measuring 10 µm by 30 µm between the voltage probes) using both optical lithography and wet chemical etching techniques [26,27]. Figure 1(c) displays an optical micrograph of a Hall bar mesa structure after wet etching.…”

Section: Resultsmentioning

confidence: 99%

Graphite/h-BN van der Waals heterostructure as a gate stack for HgTe quantum wells

Liang,

Shamim,

Chen

et al. 2024

Nanotechnology

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Two dimensional topological insulators have attracted much interest due to their potential applications in spintronics and quantum computing. To access the exotic physical phenomena, a gate electric field is required to tune the Fermi level into the bulk band gap. Hexagonal boron nitride (h-BN) is a promising alternative gate dielectric due to its unique advantages such as flat and charge-free surface. Here we present a hexagonal boron nitride/graphite van der Waals heterostructure as a top gate on HgTe heterostructure-based Hall bar devices. We compare our results to devices with h-BN/Ti/Au and HfO2/Ti/Au gates. Devices with a h-BN/graphite gate show no charge carrier density shift compared to as-grown structures, in contrast to a significant n-type carrier density increase for HfO2/Ti/Au. We attribute this observation mainly to the comparable work function of HgTe and graphite. In addition, devices with hexagonal boron nitride gate dielectric show slightly higher electron mobility compared to HfO2-based devices. Our results demonstrate the compatibility between layered materials transfer and wet-etched structures and provide a strategy to solve the issue of significant shifts of the carrier density in gated HgTe heterostructures.

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Section: Resultsmentioning

confidence: 99%

Graphite/h-BN van der Waals heterostructure as a gate stack for HgTe quantum wells

Liang,

Shamim,

Chen

et al. 2024

Nanotechnology

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“…Our nano-fabrication method can also be easily adapted to other materials, such as HgTe/HgCdTe heterostructures [34], ZnO/Ge core-shell nanowires [35] or silicon devices [30,36], where the wet etching is an essential processing step. Notably, the electron beam exposure can be helpful when post-processing allows intense oxygen ashing of the remaining negative resist.…”

Section: Discussionmentioning

confidence: 99%

Wet etching of gold on graphene for high-quality resist-free graphene surfaces

Kunc,

Shestopalov,

et al. 2023

Nano Ex.

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Wet etching of gold on graphene is challenging due to the weak adhesion of the resist mask to graphene. We report an operating procedure for alkali ion-free wet etching of gold on graphene using a mixture of hydrochloric and nitric acids (aqua regia) with a high lateral resolution down to 100~nm. We investigate the role of positive and negative resists, electron beam lithography (EBL) dose, hard-bake, oxygen etching, aging, and sensitivity to the etch parameters, such as the freshness of dilute aqua regia, etch time, and the order of etched samples. The negative-tone resist provides the best results. The over-dosed EBL exposure can enhance the resist adhesion, as hard-bake below the glass-transition temperature and well-defined wet etch of the resist-residua-free gold surface. We also present a cleaning procedure to avoid bubble formation after the hard bake. Our results demonstrate that wet etching of gold on graphene using aqua regia is a viable method for achieving high-quality resist-free graphene surfaces. This method has potential applications in graphene nanoelectronics and nanophotonics, where high-quality graphene surfaces are essential for device performance.

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Realization of smooth side profile using diffusion-controlled wet chemical etching for HgTe/(Hg,Cd)Te heterostructures

Cited by 2 publications

References 28 publications

Graphite/h-BN van der Waals heterostructure as a gate stack for HgTe quantum wells

Graphite/h-BN van der Waals heterostructure as a gate stack for HgTe quantum wells

Wet etching of gold on graphene for high-quality resist-free graphene surfaces

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