Photodetection Module Mounting for Low-Inductance Beat Spectroscopy

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Photodetectors require improvements in response speed and reliability, particularly in quantum cascade detectors, and existing technologies struggle to widen the wavelength scanning range in beating spectroscopy devices.

Innovation Solution

A photodetection module with a photodetector connected to a fixing member via surface contacts and recessed wiring, reducing inductance and protecting delicate mesa portions, and a beating spectroscopy device that incorporates this module to enhance response speed and scanning range.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If wire bonding is used to connect the first electrode and the first wiring, then electrical connection is achieved, but inductance increases and response speed decreases

Engineering Contradiction:

Improveresponse speedVSAvoidinductance

Core Design Contradiction:

SpeedVSDevice complexity

Solution Approach 1:

The patent extracts and eliminates the wire bonding connection method that introduces inductance. Instead, it uses a direct surface contact connection between the first electrode and the first wiring through the recessed portion, removing the harmful inductive element while maintaining electrical connectivity.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The recessed portion in the insulating substrate acts as an intermediary structure that enables direct surface contact between the first electrode and the first wiring. This intermediary feature facilitates low-inductance connection without requiring traditional wire bonding techniques.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If the mesa portion is exposed on the surface, then access is easy, but the delicate mesa portion is vulnerable to damage

Engineering Contradiction:

Improveprotection of mesa portionVSAvoidaccess to mesa portion

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The mesa portion is nested within the recessed portion of the insulating substrate. This nesting structure provides mechanical protection to the delicate mesa portion while maintaining its functional accessibility for light incidence and electrical connection.

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The recessed portion serves as a protective cushioning structure that is prepared in advance to shield the delicate mesa portion from mechanical damage, environmental stress, and handling errors before any potential damage can occur.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Reliability

If the first electrode and first wiring are connected with large contact area, then connection strength increases, but parasitic capacitance increases and response speed decreases

Engineering Contradiction:

Improveconnection strengthVSAvoidresponse speed

Core Design Contradiction:

ReliabilityVSSpeed

Solution Approach 1:

The patent applies local quality by creating a contact area that is locally optimized within the recessed portion. The contact provides sufficient strength for reliable connection while maintaining a controlled size to minimize parasitic capacitance, achieving local optimization of both mechanical and electrical properties.

Inventive Principle:

Principle #3Local quality

4Speed

If traditional photodetector mounting is used, then assembly is simple, but inductance and parasitic effects limit response speed and wavelength scanning range

Engineering Contradiction:

Improveresponse speedVSAvoidmounting structure

Core Design Contradiction:

SpeedVSDevice complexity

Solution Approach 1:

The patent transitions from traditional planar mounting to a three-dimensional structure by creating a recessed portion in the insulating substrate. This dimensional change allows the first electrode to contact the first wiring at a lower level, reducing inductance and parasitic effects while maintaining assembly feasibility.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

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 response speed and ensures reliability by minimizing inductance and protecting sensitive components, allowing for a wider wavelength scanning range in beating spectroscopy.

Implementation Method 1

The quantum cascade detector detects light using intersubband transition (intersubband absorption) in a quantum well structure

Methodology Applied

Scientific EffectIntersubband absorption: Absorption (EM radiation)

Data Source

PatentUS12520615B2Light detection module and beat spectrometer

Publication Date: 2026.01.06 HAMAMATSU PHOTONICS KK

AI summary

A photodetection module includes a photodetector and a fixing member. The photodetector includes a semiconductor substrate, a mesa portion, a first contact layer, a second contact layer, and a first electrode formed in a planar shape on a major surface of the semiconductor substrate, and electrically connected to one of the first contact layer and the second contact layer. The fixing member includes an insulating substrate, and a first wiring formed in a planar shape on a major surface of the insulating substrate. A recessed portion is formed in the major surface of the insulating substrate, and at least a part of the mesa portion is disposed inside the recessed portion. The first electrode is electrically connected to the first wiring in a state where the first electrode is in surface contact with the first wiring.