Multi-Heterojunction HEMT Structure for Transconductance Linearity
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Solution Overview
Problem
The linear operating characteristics of high electron mobility transistors (HEMT) devices are compromised due to increased series resistance and decreased electron saturation speed, leading to reduced transconductance and linearity, especially as gate-source bias voltage increases.
Innovation Solution
A semiconductor structure with a protrusion structure featuring sequentially stacked heterojunctions, where at least one barrier layer is doped with an N-type element, allowing for controlled two-dimensional electron gas concentration and threshold voltage adjustment, thereby enhancing transconductance linearity and stability across a wide gate-source bias voltage range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the total barrier layer thickness is increased to achieve multi-channel heterojunction structure, then the total concentration of 2DEG increases and device saturation current increases, but the distance between gate and underlying channel increases, reducing gate control ability and peak transconductance
Solution Approach 1:
The barrier layer is divided into multiple segments (first barrier layer, second barrier layer, third barrier layer) with different thicknesses and doping concentrations. The first barrier layer has higher doping concentration and smaller thickness, while subsequent layers have lower doping concentrations and larger thicknesses, creating a gradient structure that segments the charge distribution to improve gate control while maintaining high 2DEG concentration
Solution Approach 2:
Different regions of the barrier layer are given different local properties through selective doping. The first barrier layer near the channel has higher doping concentration to enhance local electric field and 2DEG formation, while upper layers have lower doping to reduce overall thickness impact on gate control, creating localized optimization of electrical properties
2Ease of manufacture
If ordinary HEMT device is used, then manufacturing is simple, but transconductance increases with gate-source bias voltage and then decreases, affecting device linearity
Solution Approach 1:
The doping concentration parameter is changed across different barrier layers, creating a gradient from high to low doping concentrations. This parameter variation modifies the electric field distribution and 2DEG profile, resulting in transconductance that remains stable and linear across a wide gate-source bias voltage range rather than peaking and declining
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
The semiconductor structure achieves improved transconductance linearity, increased peak transconductance range, reduced contact resistance, and enhanced frequency characteristics while maintaining stable electric properties, effectively addressing the limitations of traditional HEMT devices.
Implementation Method 1
at least one of the first barrier layer, the second barrier layer, . . . or the n-th barrier layer is/are doped with an N-type element
Implementation Method 2
the increase in the total concentration of 2DEG, which substantially increases the device saturation current
Data Source
AI summary
The present disclosure provides a semiconductor structure including a substrate, an insulation layer on the substrate; a protrusion structure protruding out of the insulation layer, where the protrusion structure includes a source region, a drain region and a channel region between whereof; the protrusion structure includes a first heterojunction structure, . . . and an n-th heterojunction structure sequentially stacked along a direction away from the substrate, where n is an integer greater than or equal to 2; the first heterojunction structure includes a first channel layer and a first barrier layer, . . . the n-th heterojunction structure includes an n-th channel layer and an n-th barrier layer, and at least one of the first barrier layer, . . . or the n-th barrier layer is doped with an N-type element; the source electrode on the source region, the drain electrode on the drain region, and the gate structure on the channel region.