Diamond UV Sensor pn Junction for 200 nm Sensitivity
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Solution Overview
Problem
Existing UV radiation sensors struggle to achieve high sensitivity and selectivity for wavelengths ≦220 nm while avoiding interference from visible and infrared radiation.
Innovation Solution
A UV radiation sensor with a vertical structure featuring a pn junction formed by two differently doped monocrystalline diamond areas, where the upper doped area is ≤ 300 nm thick, and the doping concentrations of the diamond layers are optimized to achieve a high spectral sensitivity ratio between 200 nm and 240 nm, reducing electrical leakage currents and enhancing selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a thicker diamond layer is used to improve structural stability, then mechanical strength is improved, but sensitivity for short-wavelength UV detection decreases
Solution Approach 1:
The patent applies segmentation by dividing the diamond structure into two distinct layers: an upper layer with thickness ≤300 nm optimized for UV detection sensitivity, and a lower layer providing structural support and mechanical stability. The pn junction is formed at the interface between these two layers, allowing each layer to fulfill its specific function - the thin upper layer captures short-wavelength UV photons efficiently while the thicker lower layer provides structural integrity.
2Ease of operation
If Schottky contacts are used for electrical contact on the diamond layer, then electrical contact is achieved, but electrical leakage currents increase during detection
Solution Approach 1:
The patent extracts the problematic Schottky contact interface by replacing it with a pn junction formed directly within the diamond layers. Instead of using metal-semiconductor contacts that generate leakage currents, the invention creates a homojunction between p-type and n-type doped diamond regions, which eliminates the Schottky barrier and associated leakage currents while maintaining effective electrical contact and detection capability.
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 sensor achieves a spectral sensitivity ratio of 1:1000, enabling high sensitivity and selectivity for UV-C wavelengths, allowing for interference-free detection of UV radiation.
Implementation Method 1
a radiation-sensitive region (10) of single-crystal diamond... forming a pn junction for radiation detection
Implementation Method 2
a material with a sufficiently large band gap, such as diamond, is suitable for the radiation-sensitive area of UV sensors
Data Source
Figure 1A~2B
AI summary
The present invention relates to a UV radiation sensor with a radiation-sensitive area made of diamond, which is formed on a first side of a semiconductor substrate (1) and can be electrically contacted via at least two contact electrodes (4, 5). In the proposed UV radiation sensor, the radiation-sensitive area has two differently doped regions (2, 3, 3') made of diamond, which form a pn junction for radiation detection. A UV radiation sensor designed in this way has high sensitivity in the wavelength range ≤ 200 nm.