Reliably & precisely transfer heterostructures

with computer-aided alignment technologies

Computer-aided Alignment

 

Nanovie HPAS Mono excels at high precision stacking - fast & accurate with imaging analysis and alignment software, superior and reliable stacking quality with 50 nm per stacking step in Z direction and adjustable tilt, minimised oxidation and contamination as operation in a glove box is handy through software control.

 

 

Stacking Procedures

Preparation: (1) Transfer the atomic layers prepared by mechanical exfoliation or CVD growth onto the targeted substrate. (2) Transfer the other atomic layers onto a transparent stamp, such as polydimethylsiloxane (PDMS).

 

1) PDMS Transfer

HPAS standard procedure 03 g

 

2) Focus and Position

HPAS standard procedure 09

 

3) Align and stack

HPAS standard procedure 11 g

 

4) Inspect

HPAS standard procedure 12 g

 

Stacking: Place the two materials on to the motor stage and the sample holder respectively. Start to align the two structures using HPAS Mono's aligning tools in the software interface. Once precisely aligned, engage the materials at 50 nm per step, disengage and complete the stacking.

 

Aligning & Stacking Tools

 

HPAS feature image overlapping

Objects at different depths could be precisely aligned by the motorised stage at XYZ 50 nm/step and 0.056° angular resolution, extending the research into magic angle graphene and anistropic materials.

 

 

Object Tracking

HPAS feature object tracking

- detects the edges in live-view mode, allowing fast & accurate alignment. Example: a sample on PMDS.

 

Contrast Enhancement

HPAS feature contrast enhancement

- improves the colour contrast in live-view mode.

 

Image Overlapping

HPAS feature image overlapping

- makes it easy to align objects at different depths under extremely shallow depth of focus by comparing images captured at different depths.

 

RGB Analysis

HPAS feature rgb analysis

- derives material thickness from the RGB contrast database with four channels (red, green, blue and grey) and distinguishes up to a few layers of 2D materials (depending on the microscope & camera module used).

 

 

Temperature Control

HPAS feature image overlapping

- allows heating from room temperature upto 150˚C (or higher) with real-time PID software control.

 

Designs for oxygen- and moisture- sensitive materials

Suitable for glove box operation - high precision alignment tasks could be completed via external software control.

 

Nanovie Product HPAS Alignment Stacking

 

Alternatively, HPAS Mono could use its own integrated inert gas chamber. All the operations, from sample preparation, placing, aligning to stacking, would be much easier without wearing multi-layered gloves.

Applications of Heterostructures Stacking

Two dimensional layered materials (2DLMs), such as semiconductors, semimetals and topological insulators, possess bandgaps in wide ranges, which offer excellent current on/off ratios that graphene doesn’t. 2DLMs could also be modulated with changing thickness, ideal for the applications in field effect transistors, photodetectors and flexible devices. The van der Waals heterostructures (vdWHs) based on 2DLMs also allow to select different materials properties for a greater versatility.

 

These 2DLM-based heterostructures could be fabricated by mechanical transfer or chemical vapour deposition (CVD) growth. The direct CVD synthesis shows promising applications in mass production, while the mechanical transfer process provides great flexibility in constructing diverse 2D heterostructures with various materials for their novel properties.

 

Typical Advantages

1. Light-Emitting Diodes

Monolayer transition metal dichalcogenides (TMDs) and black phosphorous, regardless of its thickness, are both ideal for light emitting due to their direct bandgaps from visible to near-infrared range. Constructing p-n diodes (LEDs) based on 2D heterostructures is proven to be effective in improving their electroluminescence (EL) performances.

 

2. Photodetectors

Photodetectors are used widely in our daily life, such as environment monitoring, video imaging, remote sensing, optical communication and military equipments. 2D layered materials offer high transparency, strong light–matter interaction, multi-functional flexibility and easy integration with metal–oxide semiconductors.

 

3. Optical Modulators

Optical modulation controls phase and intensity of incident light. It is one of the most crucial operations for optical interconnect, security and medicine, and 2D layered materials provide multifunctional applications with different mechanisms, including electro-optic, thermo-optic and other approaches.

 

Features & Specifications

  • HPAS Mono (High-Precision Alignment Stacking), equipped with professional computer-aided alignment technologies, is able to precisely align the hetereostructures or 2D materials during the stacking process.

     

    Sub-micron Precision Stage
    • XYZ resolution ≈ 50 nm/step
    • Rotation resolution ≈ 0.1°
    • Travel range XYZ ≈ 2 x 2 x 5 cm
    • Computer-aided stage control

     

    Computer-aided Alignment
    • Live-view operation
    • Computer-aided focus
    • Contrast enhancement
    • Object tracking
    • Image overlapping
    • RGB thickness analysis

     

  • HPAS Mono is well integrated with a professional-grade objective and a high-sensitivity camera to perform the highly demanding alignment tasks.

     

    Objective*
    • Magnification = 20 X
    • Numeric aperture = 0.45
    • Assisted illumination

     

    Camera*
    • High sensitivity sensor
    • Static Resolution: 6 MP
    • HD Video: 1080p

     

    * The above could be customised and subject to changes without notice.

  • List of typical applications:

    • Photovoltaic cells / photodetectors
    • Interface / contact improvement
    • Light-emitting / tunnelling diodes
    • Electrolyte / logic gates
    • Suspended devices
    • Metal mask alignment
    • Nanoscale electronics

     

    Use for heterojuctions:

    2D/3D junctions

    For example, vertically-stacked hybrid photodiodes consisting of thin n-type MoS2 and p-type silicon p–n diodes.


    2D/2D junctions

    For example, vertical structures made of monolayer MoS2 and WSe2 demonstrate excellent current ratification behaviour and external quantum efficiency.


    2D/1D junctions

    For example, MoS2 and carbon nanotubes (CNTs). Spread nanoparticles, nanowires and other 1D materials on the substrate or PDMS and transfer to other 2D materials, creating novel surface interface phenomena.


     

    Typical heterostructure-based devices:

    LED materials:
    • Gr / hBN / WSe2 / hBN / Gr
    • hBN / WSe2 / hBN
    • p-MgNiO / perovskite / n-MgZnO
    • Gr / WS2 / hBN
    • p-WSe2 / n-WSe2
    • n-MoS2 / p-MoS2 / p-GaN
    • MoS2 / Si
    • p-WSe2 / i-WSe2 / n-WSe2
    • Al2O3 / MoS2 / GaN
    • hBN / Gr / hBN / WSe2 / hBN / MoS2 / hBN / Gr / hBN
    • Gr / hBN / WS2

    * Gr: graphene

     

    Photodetector materials:
    • BP / MoS2
    • WSe2 / BP / MoS2
    • MoS2 / BP
    • InSe / Gr
    • MoTe2 / MoS2
    • PbS / Gr
    • SnS2 / MoS2
    • MoS2 / hBN/Gr
    • WS2 / MoS2
    • CdS / MoS2
    • GaSe / GaSb
    • MoS2 / GaAs
    • Gr / hBN / MoTe2
    • MoS2 / hBN / Gr
    • MoS2 / Gr / WSe2
    • GaTe / MoS2
    • PbS / MoS2
    • SnSe2 / BP
    • Gr / MoS2
    • ReSe2 / MoS2
    • WSe2 / GaSe
    • GaSe / InSe
    • BN / WSe2 / hBN
    • Gr / Mo
    • S2 / Gr
    • Gr / WS2 / Gr
    • GO / Si
    • BiI3 / WSe2
    • MoTe2 / Gr

    * GO: graphene oxide

     

  • HPAS Mono is a compact tabletop alignment stacking station that offers the complete professional grade functions required to carry out the cutting-edge stacking tasks.

     

    Main Body:

    • Dimension (mm): 450 X 300 X 500(H)
    • Weight (kg): 18 kg
    • Power: DC 12V 10A (In: 100-240V AC @ 50/60Hz)
    • Sample Working Space(mm): 20 X 20 X 50(H)
    • Sample Size (mm) < 20 X 20

     

    Computer Minimum Requirements:

    • OS: 64-bit Windows 7, 8 or 10
    • CPU: Intel i5 quad-core with 8GB RAM
    • USB: 2 Ports