Student projects

General information

A lump sum of CHF 600.- for transportation expenses’ support will be given to each student doing his/her semester project in AQUA in Neuchâtel.

A lump sum of CHF 1600.- for transportation expenses’ support will be given to each student doing his/her Master project in AQUA in Neuchâtel.

Doing a part of the project in Lausanne can be discussed. The lump sum would then be adapted proportionally to the number of trips to Neuchâtel.

No refund of effective fees will be provided. We advise students coming to do a project in Neuchâtel to buy a half-fare subscription.

 

Master projects

SiPM Characterization and 3D Imaging Applications

Description

Imaging with three dimensional information has emerged as a powerful technique for a wide variety of applications, such as autonomous driving, AR/VR, robotics and biomedical imaging. Silicon photomultipliers (SiPMs) are widely used in 3D imaging and LiDAR (light detection and ranging) thanks to their large area, high sensitivity, multi-photon detection capability and semi-commercial process integration. Combined with circuits like time-to-digital converters and standard optics, a compact time-of-flight 3D imaging system can be achieved with commercial SiPMs. Moving beyond depth imaging, the time-of-flight technique has been also used for non-line-of-sight imaging and imaging through scattering materials.

Objectives

We have recently designed a SiPM in a standard CMOS Image Sensor technology. The device has been proved to work after preliminary measurement. The student will take part in a comprehensive project including electronics, optics and computational imaging. Starting with the SiPM characterization, the student will get familiar with the principle of single-photon avalanche diodes (SPADs), which is the core of a SiPM, and master basic electrical instruments and optical setup; this will enable him/her to optimize the system and extend to attractive applications like LiDAR and non-line of sight imaging.
• SiPM characterization with tools like oscilloscope, laser, optical setup etc.
• Embedded system development including PCB design, FPGA firmware development (VHDL or Verilog).
• Algorithm implementation with well-known computational imaging techniques (Matlab).
Through this project, the student will gain hands-on experience in electrical design, measurement, optics, firmware, algorithm development, and apply them in the hot topic of integrated 3D imaging system.

Project Type: Master Thesis

Official Start Date: ASAP
Submission of Final Report: TBD
Presentations at Group Meeting: TBD

Contact Jiuxuan Zhao: [email protected]

Developing high density metal-insulator-metal (MIM) capacitors for integrated electronic-MEMS chips

Description

MIM capacitors are high density capacitors that are mainly built in the bulk of the chip. The high density is achieved by deep vertical etching through the bulk and depositing capacitors electrodes and dielectric over the walls of the trenches. In our specific application (single photon detectors), we are integrating the read-out electronic chip and the detectors in a 3D fashion. In order to block the DC offset from the detector to the high-band-width low-noise amplifier (LNA), large capacitors (order of a few nF) may be required. In this project you will design, simulate and micro-fabricate (at CMi) the capacitors. You will earn invaluable experience working with various fabrication machines, MEMS design software and also knowledge on the RF electronics, both design and simulation.

Sections related to this project:  SMT-STI

Style of research: Experimental

Supervisors: Mohammad Beygi, Emanuele Ripiccini

Contact: [email protected] and [email protected]

Design, simulation and fabrication of a rotating magnetic field to steer electrons in a micro-channel-plate (MCP) structure

Description

MCP is a planar structure with micron diameter size channels formed inside the structure used for detecting single photons. This device has application in detection of gamma-rays for positron emission tomography (PET) imaging. The angle by which the electrons make the first incident on top of the channels can determine the secondary electron gain on the bottom of the channel. The trajectory of the electron and their momentum from the photocathode to the entrance of the channels are controlled by a large electric field within this space. If a magnetic field is added to this structure which can be steered, then the path of the electrons and subsequently the incident angle can be manipulated. In this project, you will design, simulate and microfabricate (at CMi) the novel method of steering magnetic field in MCPs. You will gain invaluable experience and knowledge working with various fabrication machines, MEMS design software and the electromagnetic simulations. A basic knowledge of an electromagnetic simulation framework is required.

Sections related to this project:  SMT-STI

Style of research: Experimental, computational

Supervisors: Mohammad Beygi, Emanuele Ripiccini

Contact: [email protected] and [email protected]

Cryo-CMOS Design of Scalable SNSPD Front-end

Motivation

Single-photon detectors and nanoscale superconducting devices are two major candidates for realizing and supporting quantum technologies. Superconducting nanowires single-photon detectors (SNSPDs) in particular, cover various applications that evolved in the quantum field for the past few years such as high-rate and long-distance quantum key distribution, satellite laser ranging, long-distance imaging and non-quantum applications like molecular spectroscopy. However, the largest SNSPD array reported so far is the kilo-pixel array. One of the main constraints to achieve

high levels of scaling in these detectors is the limited power budget available within the cooling system.

The architectures demonstrated so far, based mainly on analog implementations [1], [2], [3], are promising. However, going beyond one thousand pixels, while maintaining low jitter, low dark counts, high efficiency, and high-count rate is really challenging. For this reason, more innovation is required to scale up SNSPD arrays.

Description

The master project consists on the design and analysis of a low power readout circuit to interface SNSPDs. The project will consist of three main phases:

  1. Study and understanding of the physics behind Superconducting detectors. In the first months, Simulations using Cadence and SPICE will be conducted to deeply understand the main limitations from an analog design perspective.
  2. Design. The student will come up or contribute in building up new ideas for a single pixel readout.
  3. Testing. The student will help in the test of some building blocks at cryogenic temperatures as well as the realization of prototypes that may be patented.

Tasks

  • Literature research.
  • Detailed analysis of the SNSPD-pixel interface on Cadence.
  • Electromagnetic analysis of the device using ADS.
  • Design of prototypes on Altium.
  • Cryogenic Analog and Digital interface testing.

[1] Emma E. Wollman et al., “Kilo pixel array of superconducting nanowire single-photon detectors,” Opt. Express 27, 35279-35289 (2019).

[2] Zhao et al. “Single-photon imager based on a superconducting nanowire delay line,” Nature Photon 11, 247–251 (2017).

[3] S. Doerner et al., “Frequency-multiplexed bias and readout of a 16-pixel superconducting nanowire single photon detector array,” Appl. Phys. Lett. 111(3), 032603 (2017).

Supervisor: Jad Benserhir, Prof. Edoardo Charbon

Location: EPFL in Microcity, Neuchâtel

Starting date: April 15th, 2021

Contacts: [email protected]

Development of a compiler from C to custom assembly language

Our laboratory has designed a custom processor for a scalable image sensor architecture. The core can run a program with a maximum length of 256 instructions, each having 24bits. An assembler was developed using Python and the output files can be directly fed into a VHDL/SystemVerilog testbench that simulates the entire system.

During the project, the student is expected to develop a simple compiler from C to the custom assembly language required by the existing framework. The main challenge comes from the limited size of the instruction memory and the custom elements in the architecture. The compiler should preferably be written in Python, but other languages can be used as well. Example assembly programs are available. All the work can be done remotely.

Contact: [email protected]

Description

Large scale SPAD cameras are successfully used in various applications. Its single photon sensitivity and CMOS compatibility make it possible to implement SPAD sensors with in-pixel circuits.

At AQUA lab, state-of-art SPAD sensors are developed. MegaX [1], the first megapixel SPAD camera with gating circuits, allows us to register only the photons impinging the detector within a certain gate window. Recent results in Figure 1 show promising performance for applications that require accurate timing, such as Fluorescence-lifetime imaging microscopy (FLIM) [2] and multidimensional imaging [3]. These results are achieved by gating operation of the camera.

In order to achieve higher photon detection efficiency and higher resolution, share pixel readout were also designed for this camera.

The student will learn about SPAD operation and how large scale SPAD camera works. The student will do HDL design for a Xilinx FPGA. The student will develop and optimize the gating mode firmware for share pixel readout architecture. The student will also learn about how to apply the developed camera on different applications, and explore new applications if time permits.

The student will be familiarized with Xilinx FPGA, and HDL design through working with a large scale SPAD camera.

Objectives

In order to achieve higher photon detection efficiency and higher resolution, share pixel readout were also designed for this camera. The student will learn about SPAD operation and how large scale SPAD camera works. The student will do HDL design for a Xilinx FPGA. The student will develop and optimize the gating mode firmware for shared pixel readout architecture. The student will also learn about how to apply the developed fully-operating Megapixel SPAD gating camera on different applications, and explore new applications if time permits.

See project link for full details.

The student will be familiarized with Xilinx FPGA, and HDL design through working with a large scale SPAD camera.

Project Type: Semester project

Official Start Date: ASAP
Submission of Final Report: TBD
Presentations at Group Meeting: TBD

Contact: [email protected]

Characterization and Analysis of Novel Photodetector Devices

General Information

Laboratory: Advanced Quantum Architecture Laboratory (AQUA)

Partners: EPFL

Supervisor: Francesco Gramuglia, Prof. Edoardo Charbon, Claudio Bruschini, PhD

Location: Microcity, Neuchâtel

Starting date: ASAP

Description

The objective of this project is to analyze the functionality and characterize novel single photon detectors based on SPADs, developed in our lab.

The activity will include optical and electrical setup implementation and devices characterization as well as firmware and software implementation.

This project can be adapted as a semester, master project or full-time internship.

For additional details, please contact us by email.

Tasks:

  • Analyze the basic performance of the devices (sensitivity and timing)
  • Firmware implementation for system readout and data analysis
  • Software implementation for data post processing (C++, Python or Matlab)
  • Deep characterization of the device performance at system level
  • Application related measurements

Expected Candidate Achievements:

  • Understanding of SPAD/SPAD arrays behavior and characteristics
  • Knowledge on how to use the setups for SPAD-based devices characterization
    • Optical setups (pulsed Laser setups, continuous light setups)
    • Electrical instruments (Supplies, Oscilloscopes, Climate chamber, etc.)
    • Embedded systems (FPGA boards, custom PCB systems)
    • Radioactive sources
  • Understanding of some of the most common applications

Candidate requirement:

  • Basic knowledge of HDL (VHDL or Verilog)
  • Basic Knowledge of programming languages (such as C++, Python or Matlab) is preferred
  • Some basics of Electronics

Contact: [email protected]

Testing of a 512×1 Event-Driven Linear SPAD Array

The objective of this project is to characterize and test the 512×1 linear SPAD array. The detector and system performance parameters to be measured are dark count rate, photon detection probability, dead time and maximum excess bias. The first task towards this goal is to develop a camera module based on a commercial FPGA board. The part to be designed is a sensor board with the chip mounted on it, which is compatible with the FPGA board. The second task is to develop the readout block of the sensor, starting from existing firmware. The lack of on-chip electronics resulting from the reconfigurable structure requires the implementation of readout modules on an FPGA, using VHDL. The firmware needs to send the control signals to the chip for the desired operational settings and collect the detected photons with their address in the array and timing delay from the laser pulse, in an event driven configuration. Finally, the information needs to be stored in the on board DDR3 RAM blocks and transferred to the PC via USB 3.0. Further specifications of the control and readout modules will be finalized depending on the details of the target application.

Details (PDF)

Contact: [email protected]

Camera Module Development for a Large Format Time-Resolved SPAD Image Sensor

The objective of this project is to develop a camera module that can perform FLIM-FRET analysis based on the existing 512×512 SPAD array. In addition to the currently available integrated SPAD sensor and two commercial FPGA integration boards, the required parts for this module are a custom designed sensor board with chip-on-board technology and a firmware written in VHDL. The firmware must control the camera operation signals from the FPGA, store the acquired data in DDR3 RAM blocks on the integration board, recover the fluorescence lifetimes in the FPGA and finally transfer the processed data to the PC via USB 3.0. The entire process must be performed in real time, where the overall speed is determined by the maximum readout speed of the sensor, 100 kfps for 1-bit images. The detailed description of the FLIM-FRET algorithm, standard MATLAB functions of the FPGA board and a test module for the half array 512×256 will be available for reference.

Details (PDF)

Contacts: [email protected]

Fabrication of InGaAs/InP based single photon avalanche detectors optimized for high efficiency at near infrared

The goal of the project is to demonstrate efficiency improvement at wavelengths below 900 nm by comparing the single photon efficiency spectrum of two InGaAs/InP SPADs with and without substrate. For this purpose student should fabricate these devices in CMi (Center of Micronanotechnology) by following various photolithography, etching, metallization and thinning processes. Following the fabrication, devices should be placed on a PCB and characterized for their photon detection efficiency. The student will have a chance to experience/perform all of the fabrication process of a single photon avalanche detector from scratch and set up an experiment to analyze the performance of the detector.

This project can be adapted as a semester or Master project.

Details (PDF)

Contact: [email protected]

 

Semester projects

Fabrication of InGaAs/InP based single photon avalanche detectors optimized for high efficiency at near infrared

The goal of the project is to demonstrate efficiency improvement at wavelengths below 900 nm by comparing the single photon efficiency spectrum of two InGaAs/InP SPADs with and without substrate. For this purpose student should fabricate these devices in CMi (Center of Micronanotechnology) by following various photolithography, etching, metallization and thinning processes. Following the fabrication, devices should be placed on a PCB and characterized for their photon detection efficiency. The student will have a chance to experience/perform all of the fabrication process of a single photon avalanche detector from scratch and set up an experiment to analyze the performance of the detector.

This project can be adapted as a semester or Master project.

Details (PDF)

Contact: [email protected]

Fabrication of high aspect ratio Though-Silicon Vias

The project is going to focus on the fabrication of high aspect ratio Through-Silicon Vias. The project will consist in three main phases.
1.       Preparation [first month]. In the first phase, the student will design the mask for the photolithography of the TSVs and will get all the trainings required by the CMi staff in order to be independent in the fabrication process. During this phase the student will learn how to design .gds files in an automatic way using the python library gdsCAD. Then, the student will help fabricate the photolithography mask she will use for the TSV design.
2.       Analysis [core of the project]. In the second phase, the student will learn how to fabricate the TSVs following two different process flows, and will show and analyze, by means of SEM images, the TSV quality difference and will extrapolate guidelines for the design process. During the fabrication, the student will sweep some parameters to assess their influence in the fabrication process:
a.       Materials used for the seed and adhesion layers deposition.
b.       TSV quality dependence with respect to the aspect ratio.
c.        TSV pitch, to assess if there is any proximity effect playing a role in the fab process and at what point it becomes relevant.
3.       Optimization [last month]. In the third and final phase, the student will, with the acquired knowledge from phase two, design and fabricate a wafer with the highest aspect ratio he/she expects to get.

Details (PDF)

Contact: [email protected]

Investigation of superconducting nanowire performance on different substrates

The project is going to focus on the fabrication and testing of impedance mismatching superconducting nanowire resonators made of NbTiN on a different range of substrates (SiO2, TiO2, Si3N4, Al2O3, AlN, AlN-on-Sapphire and MgO). The student is going to perform an analysis similar to what has been shown by Zhang and You [7], but focusing on the achievable depairing current fraction [8] of the thin films grown on different substrates. The student will develop skills in fabrication processes, cryogenics, data acquisition and data analysis.

Details (PDF)

Contact: [email protected]