The Fundamental Issue
Binary bits (1's and 0's) are the fundamental units used to process and store information in modern electronic devices. Transistors are electrical switches that mediate the two binary states (current ON and current OFF). Integrated circuits (IC), composed of transistors connected by wires (or “interconnects”), are the cornerstone of the modern computer.
The performance of ICs has improved as they become smaller. Miniaturization also has led to a decrease in power consumption. However, in the past decade, despite transistors becoming extremely small, the decrease in power consumption, as reflected by lower operating voltage, has slowed considerably.
As a transistor becomes extremely small, the operating voltage has not decreased substantially because of increasing leakage in the OFF state. The transistor still requires an operating voltage close to 1 Volt. The wires connecting the transistor, however, could function with only a few millivolts if there were a millivolt switch. Since energy consumption is proportional to the square of operating voltage, the energy currently used to manipulate a single bit of information today is 106 times greater than needed be in an ideal system.
Besides energy for switching, an IC chip also consumes energy for communications among the transistors, through the interconnects. The power consumed by interconnects in a microprocessor chip, as high as 50% even a decade ago, has continued to rise steadily to a larger portion of the total consumed power.
Thus, the entire problem of energy consumption by ICs must include tackling the energy consumption by transistors and interconnects.
The Center’s research focuses on investigating the science and establishing novel technologies for ALTERNATIVES to the conventional transistor and the metallic wire. E3S researchers of different disciplines and in multiple academic institutions are working collaboratively to make fundamental and conceptual breakthroughs in the underlying physics, chemistry, and materials science that will form the foundation for making electronic components with dramatically lower power consumption.
The Center is pursuing four scientific approaches:
In addition, the Center recognizes that its research in novel electronics components must be guided by circuit/system perspectives. The detailed technical goals/specifications for the novel electronic components in the context of a circuit is itself a research endeavor. This research activity of the Center is known as System Integration.
Switch: The Center’s goal is a switching device that can operate with a few millivolts. This goal can alternatively be stated as a switch that is ultra-sensitive while maintaining the same switching speed. For a millivolt switch to be practical, it must also have other attributes, like an appropriate On-Off ratio and a current density that is comparable to that of the conventional transistor.
|Target for the New Switch|
|Steepness:||~1 mV⁄decade||allowing switching with a few mVolts|
|On/Off Current Ratio:||106:1|
|Current or Conductance Density:||1 mS⁄μm||i.e., 1 μm device should conduct ~1 kΩ in the On state|
Optical Interconnect: The Center’s goal is to enable transistors in future microprocessors to communicate optically versus electrically, as in conventional IC chips. This goal calls for tiny ultra-efficient light sources and ultra-sensitive detectors that are at the scale of transistors; i.e., a reduction in component sizes to nanometer dimensions. The Center seeks to achieve communications on the chip close to the fundamental limit of optical communication, i.e., 20 x 10-18 joules per bit; i.e., a reduction of energy used per bit to communicate by four orders of magnitude.