Optical Semiconductor Device Low-Voltage Electrode Ion Trapping
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Solution Overview
Problem
Conventional optical semiconductor devices, such as avalanche photodiodes, suffer from moisture-related issues like leakage current and corrosion when used in high humidity environments, leading to discoloration and degradation, which can result in short-circuits and operational failures.
Innovation Solution
The implementation of a low-voltage electrode surrounding the anode electrode, which applies a voltage lower than the cathode electrode, effectively traps positive ions and prevents them from accumulating around the anode, thereby reducing discoloration and degradation, thus enhancing the anti-moisture properties of the device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a reverse bias voltage is applied to the anode electrode for avalanche multiplication operation, then the device can detect light signals with high sensitivity, but positive ions are attracted to the anode electrode causing leakage current and surface degradation in humid environments
Solution Approach 1:
A low-voltage electrode is introduced as an intermediary component between the high-voltage anode electrode and the environment. This intermediate electrode captures positive ions before they can reach the anode electrode surface, preventing ion accumulation and subsequent moisture-related degradation while preserving the avalanche multiplication function.
2Reliability
If the device is hermetically sealed to prevent moisture infiltration, then anti-moisture property is improved, but manufacturing complexity and strict control requirements increase
Solution Approach 1:
The harmful positive ions are extracted and captured by the low-voltage electrode before they can cause damage to the device surfaces. This extraction approach eliminates the need for complex hermetic sealing structures, as the ion capture mechanism prevents degradation without requiring complete isolation from the external environment.
3Device complexity
If charged ions are allowed to accumulate around the anode electrode, then the device structure remains simple, but leakage current increases and causes surface corrosion and discoloration
Solution Approach 1:
The low-voltage electrode serves as a mediator that intercepts positive ions in the vicinity of the anode electrode. By placing this intermediate component, the device maintains structural simplicity while effectively preventing ion accumulation, leakage current, and surface corrosion without requiring complex modifications.
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 configuration significantly reduces the occurrence of discoloration and degradation, allowing the optical semiconductor device to function effectively in high humidity environments without the risk of short-circuits, as demonstrated by experiments under controlled conditions of 85% humidity and 85°C.
Implementation Method 1
a low-voltage electrode which is arranged so as to surround the second electrode and to which a voltage lower than that of the first electrode is applied
Implementation Method 2
a surface protection film which covers top surfaces of the first conductive type semiconductor layer and the second conductive type semiconductor region
Implementation Method 3
enter the n-type InP layer 13 to which a high electric field is applied, provokes avalanche multiplication under such a high electric field and produces many new electrons and holes
Data Source
AI summary
An n-type InGaAs light absorbing layer and an n-type InP layer (first conductivity type semiconductor layer), which is a window layer, and a multiplication layer are multilayered one atop another on an n-type InP substrate. By selectively diffusing impurities and implanting ions, a p-type InP region second conductivity type semiconductor region) is formed on a part of the top surface of the n-type InP layer. The top surfaces of the n-type InP layer and p-type InP region are covered with a surface protection film. A cathode electrode (first electrode) is connected to the underside of the n-type InP substrate. A ring-shaped anode electrode (second electrode) is connected to the top surface of the p-type InP region. A low-voltage electrode surrounds the anode electrode. A voltage lower than that of the cathode electrode his applied to this low-voltage electrode.