Heterojunction Photodetector Layout for Faster Electron Transfer

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Heterojunction photodetectors suffer from low electron transfer rates and dark current leakage due to defects at the heterojunction interface, primarily caused by lattice mismatch and band offset between different semiconductor materials.

Innovation Solution

A photodetector device with a channel region doped opposite to the absorption region at the heterojunction interface, forming a p-n junction to enhance electron transfer and reduce dark current, accompanied by a lightly doped layer to increase photo-electron collection efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If heterojunction photodetectors use different semiconductor materials to extend spectral response, then detection capability is improved, but lattice mismatch and band offset cause defects that increase dark current leakage

Engineering Contradiction:

Improvespectral response rangeVSAvoiddark current leakage

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

An intermediate layer with graded composition is introduced between the semiconductor materials with different bandgaps. This intermediate layer gradually transitions the composition from one material to another, reducing the abrupt lattice mismatch and band offset that cause defects and dark current leakage, while still enabling extended spectral response detection capability

Inventive Principle:

Principle #24Intermediary (Mediator)

2Speed

If heterojunction photodetectors use different semiconductor materials, then electron transfer rate is improved, but interface defects reduce reliability

Engineering Contradiction:

Improveelectron transfer rateVSAvoidinterface defect density

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

The intermediate layer is positioned specifically at the heterojunction interface where defects occur, providing localized quality improvement. This layer has graded composition that locally addresses the interface defects without altering the bulk properties of the main semiconductor materials, thus maintaining high electron transfer rate while reducing interface defect density

Inventive Principle:

Principle #3Local quality

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 increases electron transfer rates and reduces dark current leakage, enhancing the performance of heterojunction photodetectors by funneling electrons through the heterojunction interface and suppressing defects.

Implementation Method 1

Image sensors are solid-state devices that are configured to convert incoming light (e.g., photons) into an electrical signal

Methodology Applied

Scientific EffectPhotoelectric effect: Photoelectric Effect

Implementation Method 2

The channel region and the multiplication region meet at a p-n junction... forming a p-n junction to enhance electron transfer

Methodology Applied

Scientific EffectElectron transfer through p-n junction: Conduction (electrical)

Data Source

PatentUS20250366230A1Photodetector device having lightly doped layer

Publication Date: 2025.11.27 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

A photodetector device is provided. The photodetector device includes a substrate; an absorption region disposed within the substrate and in proximity to a surface of the substrate; a multiplication region disposed within the substrate and separated from the absorption region; and a channel region disposed between the multiplication region and the absorption region. The channel region and the multiplication region meet at a p-n junction. The absorption region includes a bulk region having a first p-type doping concentration; and a lightly doped layer under the bulk region and in proximity to a bottom side of the absorption region. The lightly doped layer has a second p-type doping concentration less than the first p-type doping concentration.