Thin-Film Semiconductor Device With Segmented Amorphous Layers
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Solution Overview
Problem
Conventional thin-film semiconductor devices face challenges in simultaneously improving off-characteristics by suppressing leakage current and reducing on-resistance.
Innovation Solution
The device incorporates a polycrystalline channel layer, a first amorphous semiconductor layer with a higher density of localized states, and a pair of second amorphous semiconductor layers with a larger band gap, along with an organic insulating layer, to enhance performance by reducing parasitic capacitance and excluding high-resistance layers from the current path.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a non-crystalline silicon layer is formed between the crystalline silicon layer and the channel protective layer to shield the electric field and suppress leakage current, then the off-characteristics are improved, but the on-resistance increases due to the high resistance of the non-crystalline silicon layer
Solution Approach 1:
The amorphous semiconductor layer is divided into two distinct layers: a first amorphous semiconductor layer with high localized state density for field shielding, and a second amorphous semiconductor layer with large band gap for low resistance conduction. This segmentation allows each layer to perform its specific function optimally without compromising the other.
Solution Approach 2:
Different regions of the amorphous semiconductor structure are assigned different material properties: the first layer (adjacent to channel protective layer) has high localized state density for electric field shielding, while the second layer (adjacent to contact layers) has large band gap for low resistance. This local differentiation resolves the contradiction between field shielding and low resistance.
2Object-affected harmful factors
If the amorphous semiconductor layer is positioned between the channel protective layer and the contact layers to serve as a current path, then the on-resistance decreases, but the ability to suppress leakage current and improve off-characteristics is compromised
Solution Approach 1:
The amorphous semiconductor layer is segmented into two functional layers with distinct properties. The first layer provides field shielding for off-state leakage suppression, while the second layer provides low resistance for on-state conduction. This segmentation allows simultaneous optimization of both on and off characteristics.
Solution Approach 2:
The dual-layer amorphous semiconductor structure combines materials with different electronic properties (high localized state density and large band gap) to create a composite structure that exhibits both field shielding and low resistance characteristics, resolving the contradiction between off-characteristics and on-resistance.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration effectively improves off-characteristics by suppressing leakage current and decreases on-resistance, leading to enhanced performance of the thin-film semiconductor device.
Implementation Method 1
The non-crystalline silicon layer 950 can shield the electric field by cancelling positive fixed charge in the channel protective layer 960 by the charge density of the negative carriers
Implementation Method 2
a pair of second amorphous semiconductor layers, one of which is positioned at a side surface on one side of the first amorphous semiconductor layer and a side surface on one side of the channel layer, and the other of which is positioned at a side surface on the other side of the first amorphous semiconductor layer and a side surface on the other side of the channel layer
Data Source
AI summary
A thin-film semiconductor device includes: a gate electrode; a channel layer; a first amorphous semiconductor layer; a channel protective layer; a pair of second amorphous semiconductor layers formed on side surfaces of the channel layer; and a pair of contact layers which contacts the side surfaces of the channel layer via the second amorphous semiconductor layers. The gate electrode, the channel layer, the first amorphous semiconductor layer, and the channel protective layer are stacked so as to have outlines that coincide with one another in a top view. The first amorphous semiconductor layer has a density of localized states higher than those of the second amorphous semiconductor layers. The second amorphous semiconductor layers have band gaps larger than that of the first amorphous semiconductor layer.