HEMT Drain Electrode Segmentation for Off-Current Reduction
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Solution Overview
Problem
Conventional high-electron mobility transistors (HEMTs) suffer from increased off-current (IOFF) and reduced breakdown voltage due to spiking defects caused by the reaction between metal drain electrodes and semiconductor layers, leading to electric field crowding and unnecessary current leakage.
Innovation Solution
A high-electron mobility transistor design featuring a substrate with a group III-V channel layer, barrier layer, and cap layer, where the first drain electrode forms a Schottky contact and the second drain electrode forms an ohmic contact, both laterally separated with an interlayer dielectric in between, optimizing electric field distribution without increasing contact area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an ohmic contact is formed between the drain electrode and the underlying semiconductor layer, then the contact resistance is kept low, but spiking defects are formed at the bottom of the drain electrode due to the reaction between the metal and semiconductor
Solution Approach 1:
The drain electrode is divided into two separate electrodes: a first drain electrode forming a Schottky contact and a second drain electrode forming an ohmic contact. This segmentation allows each electrode to perform its specific function independently - the Schottky contact provides high electric field distribution while the ohmic contact provides low contact resistance, eliminating the spiking defects that would occur with a single ohmic contact electrode.
Solution Approach 2:
Different regions of the drain contact structure are given different contact types tailored to their specific functional requirements. The first drain electrode region uses Schottky contact properties for optimal electric field distribution, while the second drain electrode region uses ohmic contact properties for minimal resistance, optimizing each local area for its specific purpose.
2Stress or pressure
If spiking defects are formed at the bottom of the drain electrode, then the electric field near the spiking defects becomes relatively high (E-field crowding), but this causes unnecessary current leakage and increases the IOFF of the HEMT
Solution Approach 1:
By segmenting the drain contact into two separate electrodes with different contact types, the electric field distribution is optimized without creating spiking defects. The Schottky contact first drain electrode provides controlled electric field distribution away from the semiconductor interface, preventing E-field crowding and the associated current leakage that would increase IOFF.
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 design reduces off-current (IOFF) and maintains low on-state resistance (RON), enhancing the reliability and performance of high-voltage semiconductor devices by improving electric field distribution and avoiding spiking defects.
Implementation Method 1
there is a Schottky contact between the first drain electrode and the underlying semiconductor layer
Implementation Method 2
there is an ohmic contact between the second drain electrode and the underlying semiconductor layer
Data Source
AI summary
A high-electron mobility transistor (HEMT) includes a substrate, a group III-V channel layer, a group III-V barrier layer, a group III-V cap layer, a source electrode, a first drain electrode, a second drain electrode, and a connecting portion. The group III-V channel layer, the group III-V barrier layer, and the group III-V cap layer are sequentially disposed on the substrate. The source electrode is disposed at one side of the group III-V cap layer, and the first and second drain electrodes are disposed at another side of the group III-V cap layer. The bottom surface of the first drain electrode is separated from the bottom surface of the second drain electrode, and the composition of the first drain electrode is different from the composition of the second drain electrode. The connecting portion is electrically coupled to the first drain electrode and the second drain electrode.