Oxide Semiconductor Schottky Diode for High Breakdown Voltage
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Solution Overview
Problem
Conventional Schottky diodes face challenges in achieving high current-voltage characteristics and mass productivity due to the use of materials like Si, GaAs, and SiC, which require high-temperature processes and are costly, especially when trying to form wide band gap semiconductors for high voltage applications.
Innovation Solution
A Schottky barrier diode element is developed using a silicon substrate with an oxide semiconductor layer having a band gap of 3.0 eV to 5.6 eV, primarily composed of indium (In) and other metals like Ti, Zn, Ga, and Sn, which offers excellent current-voltage characteristics and high dielectric breakdown fields, while being cost-effective and suitable for mass production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If Si-based schottky diode is used for high-speed switching, then switching speed is improved, but band gap is limited to 1.1 eV requiring larger element size for high voltage applications
Solution Approach 1:
The patent uses a layered composite structure combining Si substrate with wide band gap compound semiconductor layers (SiC, SiGe, GaN, AlN) to achieve both high-speed switching performance and high withstand voltage capability. The compound semiconductor layer forms the Schottky barrier interface while the Si substrate provides mechanical support and electrical connection.
Solution Approach 2:
The invention applies different material properties to different regions: the compound semiconductor layer provides high breakdown field and wide band gap for voltage handling, while the Si substrate provides high carrier mobility for fast switching. This local differentiation of material functions resolves the contradiction between speed and voltage capability.
2Reliability
If GaAs is used to achieve higher band gap (1.4 eV) and superior withstand voltage, then voltage capability is improved, but epitaxial growth on Si substrate is difficult causing dislocation
Solution Approach 1:
The patent introduces SiC, SiGe, or GaN as intermediate buffer layers between the GaAs active layer and the Si substrate. These intermediary layers have lattice constants that gradually transition from Si to GaAs, reducing dislocation density and enabling high-quality GaAs growth on Si substrates.
Solution Approach 2:
The semiconductor structure is segmented into multiple functional layers: Si substrate, buffer layers (SiC/SiGe/GaN), and GaAs active layer. This segmentation allows each layer to be optimized independently for its specific function while managing the interface between mismatched materials.
3Reliability
If SiC is used to achieve wide band gap (3.3 eV) and high dielectric breakdown field, then voltage capability is improved, but high-temperature production process reduces mass productivity
Solution Approach 1:
The patent utilizes the phase transition property of AlN from solid to liquid at relatively low temperature (1100-1200°C) to enable low-temperature processing. By controlling the melting and solidification of AlN in situ, the invention achieves wide band gap semiconductor formation without requiring high-temperature epitaxial growth, thereby improving mass productivity.
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 solution provides a Schottky barrier diode with improved current-voltage characteristics and high dielectric breakdown fields, enabling the use of wide band gap semiconductors at a lower cost and with enhanced mass productivity, suitable for various electronic and automotive applications.
Implementation Method 1
a schottky barrier diode element having a silicon (Si) substrate, an oxide semiconductor layer and a schottky electrode layer
Implementation Method 2
a diode having rectification function utilizing an electron barrier formed in the interface of a metal and a semiconductor
Data Source
AI summary
A schottky barrier diode element having a silicon (Si) substrate, an oxide semiconductor layer and a schottky electrode layer, wherein the oxide semiconductor layer includes a polycrystalline and/or amorphous oxide semiconductor having a band gap of 3.0 eV or more and 5.6 eV or less.