Nitride Semiconductor Drain Electrode Field Alleviation
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Solution Overview
Problem
In horizontally-structured nitride semiconductor devices, when turned off, a high drain voltage can cause the depletion layer to extend up to the drain electrode, concentrating the electric field and potentially damaging the element.
Innovation Solution
The semiconductor device incorporates a first and second nitride semiconductor layer with varying aluminum concentrations and thicknesses, along with a nitride layer stack, to create regions with increased sheet carrier concentration, thereby suppressing the depletion layer's extension towards the drain electrode and alleviating electric field concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high drain voltage is applied to turn off the device, then the depletion layer extends to suppress carrier conduction, but the electric field concentrates at the drain electrode causing potential damage
Solution Approach 1:
The patent applies local quality by creating a guard ring electrode structure specifically at the drain electrode region. This guard ring is positioned at a different potential than the main drain electrode, creating a localized electric field distribution that prevents field concentration at critical points while maintaining the overall high voltage blocking capability of the device.
Solution Approach 2:
The guard ring electrode acts as an intermediary element between the main drain electrode and the semiconductor structures. By introducing this intermediate electrode at a controlled potential, the patent mediates the electric field distribution, preventing direct field concentration at the drain electrode while still allowing the depletion layer to form for carrier suppression.
2Reliability
If the depletion layer is allowed to extend fully to suppress carriers, then conduction is effectively blocked, but the electric field concentrates and damages the element
Solution Approach 1:
The patent applies preliminary anti-action by pre-positioning the guard ring electrode at a specific potential before the full depletion layer forms. This preliminary electric field configuration counteracts the tendency of the depletion layer to extend excessively, preventing the harmful field concentration before it can cause damage to the element.
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 effectively suppresses the depletion layer's extension towards the drain electrode, enhancing the reliability of the semiconductor device by reducing electric field concentration and improving its operational integrity.
Implementation Method 1
When a horizontally-structured nitride semiconductor device is turned off, a two dimensional electron gas previously formed therein below the gate electrode is depleted. At this time, when a drain voltage is high, in some cases, a depletion layer extends up to the drain electrode. In this case, an electric field concentrates at the drain electrode
Implementation Method 2
a first nitride semiconductor layer, a second nitride semiconductor layer containing aluminum located on the first nitride semiconductor layer
Data Source
AI summary
A semiconductor device includes a first nitride semiconductor layer, a second nitride semiconductor layer containing aluminum located on the first nitride semiconductor layer, one or more nitride layers containing aluminum located on the second nitride semiconductor layer, a source electrode located on the second nitride semiconductor layer, a drain electrode located on one of the second nitride semiconductor layer or the nitride layer, and a gate electrode located between the source electrode and the drain electrode. An end of the nitride layer on the source electrode side thereof is located between the gate electrode and the drain electrode.