Below are the MSc and BSc assignments currently available in the group Semiconductor Components. All assignments can be done in the BSc and the MSc setting, unless otherwise stated.
Literature survey LED/LED drivers
As mentioned before, the novelty in the approach proposed by NRGLed implies that there will be hardly any scientific publications about this concept. However it would be advisory to verify this by performing an elaborate literature survey, including patents (before February 2008).
The literature survey should focus on the following aspects:
- Alternative principles of transforming (voltage/current) electric power in addition to SMPS
- LED driving with power values that are at least a factor of 5 higher than the specified power values
- Various applications of PWM in combination with LEDs
- Optical efficiency of LEDs: what are the important parameters and where are the limits
- Resistive behavior of LEDs and heat generation inside the LEDs
- Transport of thermal energy for various LED production techniques
- Crucial factors which determine the lifetime of the LED
The ideal power transistor is cheap to produce, can switch enormous currents, and withstands high voltages in the off-state.
Real power transistors are not that good yet… we have some ideas how to improve the power transistor of today, and students can help us test those ideas, improve them, and verify them using computer models, semiconductor physics theory, and (in some cases) measurements on real transistors we collected from industry.
Wild transistor ideas for ultra-low power chips
In digital logic chips, such as microprocessors, the leakage power consumption is getting out of hand when we keep making transistors smaller. The problem is simple: an old-fashioned mechanical switch does not leak any current when it is “off”, but a transistor does.
In the past few years, we’ve been brainstorming with colleagues in our field how to make a very small switch that turns off much better than a classical transistor. Proposals include the use of extremely thin silicon layers (silicon-on-insulator), quantummechanical tunneling, or the piezoelectric effect.
Multi parameter sensor
A mass flow sensor measures the mass flow of a gas or liquid. Several sensing mechanisms exist, e.g. thermal, Coriolis, pressure drop, drag force, which are dependent on the fluid properties in different ways. Therefore, by integrating several flow sensing structures on the same chip one can combine the output signals and extract parameters from the fluid (e.g. density, viscosity) or get an estimate of the composition of the gas or liquid. In this field several assignments are possible, e.g. measure the composition of medicine mixtures or measure the fat content of milk.
When the CMOS chip is complete, we can build additional structures on top of it. For instance, we can make micromechanical structures, infrared detectors, or solar cells on top of a chip, and connect them electrically to this chip. This produces extremely compact microsystems.
Here is a collection of MSc and BSc assignments that include microfabrication in the MESA+ Nanolab. You will be trained to work in this lab and manufacture and test new prototypes. Most assignments will make use of Atomic Layer Deposition to make (sub)nanometer thin layers.
The light-emitting diode or LED is basically a p-n junction with a lowly doped (“intrinsic”) region in between that forms the active region for light emission. It would be interesting to have LEDs integrated with CMOS. There are several possible methods to do so such as employing alternative materials e.g. Gallium-Nitride (GaN) integrated in silicon or improved silicon LEDs in the near-visible wavelength.
Capacitive readout of a Coriolis mass flow sensor
A Coriolis mass flow sensor consists of a vibrating tube in which a flowing gas or liquid experiences Coriolis forces. In our sensor chips the movement of the tube is measured capacitively. Using additional electrodes it seems possible to tune the sensitivity of the sensor by simply adjusting the amplitudes of the readout signals. In this assignment you will investigate this effect experimentally.
For high-frequency signal processing, specialized integrated circuit technologies are developed, for instance MMIC’s. In our group we study RF devices that can be integrated in the standard CMOS platform technology, such as varactors, varicaps and resonant-gate field-effect transistors.
Catalytic micro scale combustion / combustion in 3D a printed device
In the Wobbe project we are aiming at realizing a miniature Wobbe index sensor to measure the energy content of natural gas. To limit the required temperature for the gas to react one can use a catalist. This assignment is all about how the flame propagation and the formed combustion products relate to the gas flow rates. This will be done by performing a thorough literature study on microscale combustion, the thermodynamics, radicals and quenching, and by performing combustion experiments inside aquartz capillary and analyzing the combustion products.
Micro-fused Silicon Strain Gauge Pressure Sensor
State-of-the-art silicon strain gauge pressure sensors are widely used throughout the automotive industry for applications ranging from brake-, transmission- and fuel pressure sensors, to occupant weight force sensing. Such pressure sensors typically consist of silicon strain gauge elements which are glass–bonded to a stainless steel diaphragm. The design of the sensor is such that it provides a linear voltage output which is directly proportional to the applied pressure on the steel diaphragm by calibration.
An initial experimental study of a novel ultra-sensitive ion-sensitive transistor
For clinical or industrial applications specific ion sensing in aqueous samples is needed at extremely low limits of detection (LODs) and with a high signal-to-noise ratio (S/N). For this purpose the ion-sensitive field-effect transistor (ISFET) can be used. In this device the gate is in contact with the aqueous solution, containing e.g. biomolecules or DNA, from which chemical charge in the solution at the gate (input) is mirrored to electric charge that governs the drain current (output). The aim is to improve this mirror function that is expressed by the transconductance: the higher the transconductance, the better this mirror function hence sensing. One way to increase the transconductance could be to operate the ISFET in a bipolar configuration. In this configuration the device is referred to as the ion-sensitive gated bipolar transistor (ISBIT).
BSc assignment ISBIT (internal)