A laboratory at Purdue University provided a critical part of the world's first transistor in 1947 – the purified germanium semiconductor – and now researchers here are on the forefront of a new germanium milestone.
The team has created the first modern germanium circuit – a complementary metal–oxide–semiconductor (CMOS) device – using germanium as the semiconductor instead of silicon.
This graphic depicts a new electronic device created at Purdue that uses germanium as the semiconductor instead of silicon. Germanium is one material being considered to replace silicon in future chips because it could enable the industry to make smaller transistors and more compact integrated circuits. (Purdue University image)
"Bell Labs created the first transistor, but the semiconductor crystal made of purified germanium was provided by Purdue physicists," said Peide "Peter" Ye, a Purdue professor of electrical and computer engineering.
Germanium was superseded by silicon as the semiconductor of choice for commercial CMOS technology. However, the industry will soon reach the limit as to how small silicon transistors can be made, threatening future advances. Germanium is one material being considered to replace silicon because it could enable the industry to make smaller transistors and more compact integrated circuits, Ye said.
Compared to silicon, germanium also is said to have a "higher mobility" for electrons and electron "holes," a trait that makes for ultra-fast circuits.
In new findings, Purdue researchers show how to use germanium to produce two types of transistors needed for CMOS electronic devices. The material had previously been limited to "P-type" transistors. The findings show how to use the material also to make "N-type" transistors. Because both types of transistors are needed for CMOS circuits, the findings point to possible applications for germanium in computers and electronics, he said.
Findings will be detailed in two papers being presented during the 2014 IEEE International Electron Devices Meeting on Dec. 15-17 in San Francisco. One paper was authored by Ye and graduate students Heng Wu, Nathan Conrad and Wei Luo, the same authors of the second paper together with graduate students Mengwei Si, Jingyun Zhang and Hong Zhou.
The material has properties that make it difficult to create an N-type contact with low electrical resistance for good current flow. However, the germanium is doped, or impregnated with impurities that alter its properties. The areas containing the most impurities have the lowest resistance. The researchers showed how to etch away the top layer of germanium, exposing the most heavily doped portion, which provides a good contact.
The etching creates recessed channels, which serve as gates needed for CMOS transistors to switch on and off. Findings show the fundamental part of the circuit, called the inverter, is the best-performing non-silicon inverter demonstrated so far, Ye said.
The research, based at the Birck Nanotechnology Center in Purdue's Discovery Park, are funded in part by the Semiconductor Research Corp.
Writer: Emil Venere, 765-494-4709, email@example.com
Source: Peide Ye, 765-494-7611, firstname.lastname@example.org
Note to Journalists: Electronic copies of the research papers are available from Emil Venere, Purdue News Service, at 765-494-4709, email@example.com
First Experimental Demonstration of Ge CMOS Circuits
Heng Wu, Nathan Conrad, Wei Luo, and Peide D. Ye*
School of Electrical and Computer Engineering, Purdue University
*Tel: 1-765-494-7611, Fax: 1-765-496-6443, Email: firstname.lastname@example.org
We report the first experimental demonstration of Ge CMOS circuits, based on a novel recessed channel and S/D technique. Aggressively scaled non-Si CMOS logic devices with channel lengths (Lch) from 500 to 20 nm, channel thicknesses (Tch) of 25 and 15 nm, EOTs of 4.5 and 3 nm and a small width ratio (Wn:Wp=1.2) are realized on a Ge-on-insulator (GeOI) substrate. The CMOS inverters have high voltage gain of up to 36 V/V, which is the best value among all of the non-Si CMOS results by the standard top-down approach. Scalability studies on Ge CMOS inverters down to 20 nm are carried out for the first time. NAND and NOR logic gates are also investigated.
Emil Venere | EurekAlert!
Did you know that the wrapping of Easter eggs benefits from specialty light sources?
13.04.2017 | Heraeus Noblelight GmbH
To e-, or not to e-, the question for the exotic 'Si-III' phase of silicon
05.04.2017 | Carnegie Institution for Science
More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.
Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...
Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.
"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...
The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.
Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...
The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...
Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.
Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...
20.04.2017 | Event News
18.04.2017 | Event News
03.04.2017 | Event News
24.04.2017 | Physics and Astronomy
24.04.2017 | Materials Sciences
24.04.2017 | Life Sciences