Shielding Element Reduces Dark Current Drift in PIN Diode Electron Detectors
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Solution Overview
Problem
PIN diodes used as electron detectors in vacuum environments suffer from parasitic dark current due to emitted electrons interacting with the insulator, causing unwanted electric potential and conductance channels, which can significantly alter the output signal.
Innovation Solution
A shielding element is positioned between the semiconductor portion and the insulator, shaped to direct radiation onto the sensing region while shielding the insulator from emitted electrons, using cathode and anode conductors isolated from each other and coupled to an insulating element to prevent electron charging of the insulator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If emitted electrons are allowed to interact with the insulator, then the insulator can be charged and create conductance channels, but this generates parasitic dark current that dramatically changes the output signal
Solution Approach 1:
A shielding element is introduced as an intermediary component positioned between the insulator and the vacuum environment. This shielding element intercepts emitted electrons before they can reach the insulator, preventing electron charging of the insulator and the formation of parasitic conductance channels. The shielding element acts as a mediator that blocks the harmful electron-insulator interaction while allowing the desired electron detection function to proceed through the PIN junction.
Solution Approach 2:
The harmful interaction between emitted electrons and the insulator is extracted or removed from the system by positioning the shielding element to physically block electron trajectories. The shielding element effectively extracts the electrons from their harmful path toward the insulator, redirecting or stopping them before they can cause charging effects and parasitic current generation.
2Object-generated harmful factors
If a shielding element is added to block emitted electrons from the insulator, then parasitic dark current is reduced, but the device structure becomes more complex
Solution Approach 1:
The shielding element is implemented as a thin film or shell structure that provides effective electron blocking while maintaining a compact and relatively simple overall device geometry. This thin-film approach allows the shielding function to be integrated into the existing device structure without requiring bulky additional components, thereby minimizing the increase in structural complexity.
Solution Approach 2:
The shielding element is positioned in the spatial dimension between the insulator and the vacuum environment, utilizing the available space in the electron trajectory path. By placing the shielding element in this intermediate spatial region, the solution effectively blocks electron-insulator interaction without requiring modifications to the planar layout or adding complexity to the existing layered structure.
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 shielding element effectively reduces the impact of emitted electrons on the insulator, minimizing parasitic dark current and stabilizing the output signal of the PIN diode by creating a barrier that reduces unwanted electron interaction.
Implementation Method 1
the shielding element may be shaped and positioned to facilitate radiation to impinge onto the sensing region of the semiconductor portion while at least partially shielding the insulator from electrons that are emitted from the sensing region
Implementation Method 2
When the primary electron hits the active area (sensing region) of the PIN diode 10 it may create an electron\hole pair in the PIN junction formed by layers 21, 22 and 23
Implementation Method 3
The PIN diode 10 is biased by a reversed bias. Due to the applied reversed bias the electrons\holes pairs flow in the PIN junction and create a current signal through the PIN diode 10
Data Source
AI summary
A sensing element that may include (a) a PIN diode that may include an anode that is coupled to an anode contact; a cathode that is coupled to a cathode contact; a semiconductor portion that has a sensing region; and an insulator that is positioned between the cathode contact and the anode contact; and (b) a shielding element. The insulator, the cathode contact and the anode contact are positioned between the shielding element and the semiconductor portion. The shielding element is shaped and positioned to facilitate radiation to impinge onto the sensing region of the semiconductor portion while at least partially shielding the insulator from electrons that are emitted from the sensing region.