Asymmetric Source-Drain Electrodes for Transistor Crystal Orientation
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Solution Overview
Problem
Existing methods for producing field effect transistors face challenges in achieving consistent performance on a large scale due to difficulties in controlling the orientation of semiconductor crystals, leading to non-uniformity and variations in charge mobility, especially as transistor dimensions decrease.
Innovation Solution
The use of source and drain electrodes with geometrically formed facing surfaces that provide different current flow directions, allowing for varying crystallographic alignment and improved uniformity of performance, along with a semiconductor comprising crystallites and a binder, facilitates consistent conductivity across transistors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional manufacturing procedures are used to produce field effect transistors, then production can be carried out using standard techniques, but the orientation of semiconductor crystals cannot be controlled leading to non-uniform performance and variations in charge mobility
Solution Approach 1:
The source and drain electrodes are designed with asymmetric geometric formation where one electrode has a different shape or orientation relative to the other. This asymmetry creates a preferred direction for crystal growth and alignment in the semiconductor layer, ensuring that crystals align in an optimum orientation relative to the current path. This resolves the contradiction by providing controlled crystal orientation (improving uniformity) through a relatively simple geometric modification of the electrodes rather than complex manufacturing processes.
2Length of moving object
If the channel length is reduced to decrease transistor size, then device dimensions are reduced, but the number of crystals bridging the channel decreases leading to greater variation in performance
Solution Approach 1:
The invention applies local quality by creating a specific geometric configuration of the source and drain electrodes that locally influences crystal growth and orientation in the channel region. The asymmetric electrode geometry creates localized fields or surface features that guide crystal alignment specifically in the critical current path area. This ensures that even in shortened channels with fewer crystals, the crystals that do bridge the channel are optimally oriented, maintaining performance consistency despite reduced transistor size.
3Reliability
If crystalline semiconductors are used to achieve higher charge mobility, then electrical performance is improved, but the non-isotropic electrical characteristics cause unpredictable performance when crystal alignment cannot be controlled
Solution Approach 1:
The asymmetric geometric formation of source and drain electrodes performs a preliminary action by establishing a preferred crystal growth direction before the semiconductor layer is fully formed. The electrode geometry pre-determines the orientation of crystals as they nucleate and grow, ensuring that high-mobility crystal orientations are achieved consistently across all devices. This preliminary structural guidance resolves the contradiction by making crystal alignment predictable through geometric design rather than relying on random growth processes.
Data Source
AI summary
This invention comprises a field effect transistor which comprises source and drain electrodes (01) which are bridged by a semiconductor which comprises semiconducting crystallites, the conductivity of the semiconductor being controlled by a gate electrode (02) which is insulated from the semiconductor and the source and drain electrodes, to which a potential is applied for controlling the conductivity of the semiconductor, in which at least part of the facing surfaces of the source and drain electrodes are geometrically formed such that they provide current flow of different directions between the electrodes through the said channel. By this means current is caused to flow through more orientations of the crystals resulting in greater uniformity of performance between different transistors when there is a degree of variable crystallographic orientation.