Manufacturing Bits: Nov. 14

GaN for electric cars; GaN gas sensors; bulk GaN templates.


GaN for electric cars
Leti is coordinating a new European project to improve the drivetrain in electric vehicles.

The so-called ModulED project will focus on the development of gallium nitride (GaN) technology for electric vehicles. The goal is to use power-based GaN devices for the motor, enabling a change from direct current to alternating current.

The three-year, €7.2 million project includes Leti’s sister institute, Liten. BRUSA Elektronik, Punch Powertrain, ZG, Siemens and Efficient Innovation are part of program. Several universities are also part of the project, such as RTWH Aachen University, Chalmers University and Eindhoven University of Technology.

Besides GaN, the group will develop processes for magnetic materials in the motor. It will also develop a modular motor architecture, transmission, cooling systems and braking systems. “Electric vehicles are a key component of the EU’s commitment to limit climate change, but current electric vehicles face challenges preventing large market acceptance, including consumer resistance due to cost and limited driving ranges,” said Bernard Strée, project coordinator at Leti. “ModulED will target these challenges via the manufacturing process, including the mass-production context, increased value-chain involvement and lifecycle analysis for optimized duration and minimized environmental impact.”

GaN gas sensors
The Georgia Institute of Technology has developed a technique that could facilitate low-cost sensing devices for environmental applications.

The technique enables GaN gas sensors to be grown on sapphire substrates. Then, the technology is transferred to metallic or flexible polymer support materials, enabling low-cost wearable, mobile and disposable sensing devices.

With the process, researchers developed a sensor. The sensor can detect ammonia at parts-per-billion levels. It can differentiate between nitrogen-containing gases, according to Georgia Tech.

The process starts by growing monolayers of boron nitride on two-inch sapphire wafers. The monolayers are grown by using an MOVPE process at 1,300 degrees Celsius. The thin boron nitride layers produce crystalline structures. They have strong planar surface connections. The vertical connections are weak, however.

Then, using MOVPE, aluminum GaN (AlGaN/GaN) devices are then grown on top the monolayers. The devices can be transferred to other substrates. All told, the process enables GaN-based sensors. So far, Georgia Tech has transferred the sensors to copper foil, aluminum foil and polymeric materials.

GaN sensors being tested. (Credit: Georgia Tech Lorraine).

“Mechanically, we just peel the devices off the substrate, like peeling the layers of an onion,” explained Abdallah Ougazzaden, director of Georgia Tech Lorraine in Metz, France and a professor in Georgia Tech’s School of Electrical and Computer Engineering (ECE). “We can put the layer on another support that could be flexible, metallic or plastic. This technique really opens up a lot of opportunity for new functionality, new devices – and commercializing them.”

Bulk GaN templates
Kyma Technologies, a developer of advanced wide-bandgap semiconductor materials technologies, has used its new K200 hydride vapor phase epitaxy (HVPE) growth tool to produce 200mm bulk GaN templates.

The templates are based on the technology from QROMIS, formerly Quora Technology. QROMIS calls its technology GaN on QST (QROMIS Substrate Technology).

The template consists of 10 microns of HVPE GaN grown on a 5-micron MOCVD GaN on QST wafer provided by QROMIS. Kyma’s K200 HVPE tool enables uniform and rapid growth of bulk GaN on a number of different substrates.

GaN on QST process flow (Source: Kyma and QROMIS)

QROMIS recently began manufacturing 200mm substrates from its foundry partner, Vanguard International Semiconductor (VIS). VIS is planning to offer GaN power device manufacturing services on 200mm from QROMIS in 2018.

QROMIS co-founder and CEO Cem Basceri said: “QROMIS’ CMOS fab-friendly 200mm diameter QST substrates and GaN-on-QST wafers represent a disruptive technology, enabling GaN epitaxy from a few microns to hundreds of microns for GaN power applications from 100V to 1,500V or beyond, in lateral, quasi vertical or vertical forms, on the same 8-inch or 12-inch production platform at Si power device cost.”