Quantum Dot Density and Crystal Quality via Sb Layer
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional methods for growing quantum dots in semiconductor devices result in low density and degraded crystal quality, leading to reduced emission efficiency and increased scattering loss due to accumulated strain and defects in quantum dot lasers.
Innovation Solution
A method involving the formation of a Sb or GaSb layer on a base semiconductor layer, followed by self-assembled growth of quantum dots, and subsequent removal of the surface Sb layer using an As raw material gas to improve crystal quality and density, with the growth of capping layers at controlled rates to maintain uniformity and high crystal quality across multiple layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If quantum dots are formed by self-assembled growth using conventional methods, then quantum dot density can be increased, but crystal quality is degraded and emission efficiency is lowered
Solution Approach 1:
An Sb layer is formed on the base semiconductor layer surface before quantum dot growth. This preliminary Sb layer serves as a catalyst and template that promotes high-density quantum dot formation while maintaining crystal quality, resolving the contradiction between density and quality
Solution Approach 2:
The Sb layer acts as an intermediary substance between the base semiconductor layer and the quantum dot layer. It facilitates the self-assembled growth process, enabling high-density quantum dots to form with preserved crystal quality by mediating the interaction between the base layer and quantum dots
2Power
If multiple quantum dot layers are stacked to improve device performance, then emission characteristics are enhanced, but strain accumulates and defects increase
Solution Approach 1:
An Sb layer is formed on each base semiconductor layer before quantum dot growth. This preliminary Sb layer in each stacked layer independently promotes uniform quantum dot formation, preventing strain accumulation and defect propagation across multiple layers while maintaining emission characteristics
Solution Approach 2:
The Sb layer modifies the growth parameters and surface properties of each quantum dot layer, enabling uniform quantum dot formation with controlled size distribution. This parameter modification prevents strain accumulation and maintains reliability across multiple stacked layers
3Reliability
If cladding layer is grown at low temperature to protect quantum dots, then quantum dot degradation is prevented, but interface roughness increases and scattering loss is elevated
Solution Approach 1:
The Sb layer acts as an intermediary between the base layer and quantum dots, improving quantum dot crystal quality and uniformity. This results in sharper quantum dot interfaces and reduced size distribution, thereby reducing scattering loss even when cladding layer is grown at low temperatures
Solution Approach 2:
The Sb layer changes the growth parameters and surface properties, producing quantum dots with uniform size and sharp interfaces. This parameter modification reduces light scattering at quantum dot interfaces, compensating for the increased scattering that would normally occur at low growth temperatures
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 approach enables the formation of quantum dots with high crystal quality and density, maintaining uniform size distribution and density across multiple layers, and enhances emission characteristics without degrading the quantum dot properties, allowing for high-speed direct modulation and reduced scattering loss.
Implementation Method 1
forming a Sb or GaSb layer on a surface of a base layer by irradiating a surface of the base layer with Sb or GaSb
Implementation Method 2
forming quantum dots by self-assembled growth
Implementation Method 3
the most popular mode is a mode called Stranski-Krastanow mode (S-K mode). S-K mode is a mode that the epitaxially grown semiconductor crystals grow two-dimensionally (into film) at the start of the growth but grow three-dimensionally on the stage where the film has exceeded the elastic limit
Implementation Method 4
removing a surface layer containing Sb deposited on a surface of the quantum dot by irradiating the surface of the quantum dot with an As raw material gas for a prescribed period of time
Implementation Method 5
growing a capping layer on the quantum dot
Data Source
Figure 1
Figure 2A~2D
Figure 3A~3C
AI summary
The method of manufacturing the semiconductor device comprises the step of forming quantum dots 16 on a base layer 10 by self-assembled growth; the step of irradiating Sb or GaSb to the surface of the base layer 10 before or in the step of forming quantum dots 16; the step of etching the surfaces of the quantum dots 16 with an As raw material gas to thereby remove an InSb layer 18 containing Sb deposited on the surfaces of the quantum dots 16; and growing a capping layer 22 on the quantum dots 16 with the InSb layer 18 removed.