Superlattice Heterostructures with Amorphous Tunneling Barriers
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Solution Overview
Problem
Conventional quantum well structures face limitations in material combinations due to lattice constant constraints, leading to restricted band offsets and limited energy levels, and struggle with forming single-crystalline semiconductor-oxide structures, which hinders the integration of optoelectronics and photonics with Si CMOS and the creation of deep quantum wells.
Innovation Solution
The development of superlattice structures composed of single-crystal semiconductor wells and amorphous barriers, allowing for independent selection of materials and formation of multiple quantum well structures through transfer printing and inorganic thin film deposition, enabling the creation of deep wells and high energy barriers suitable for quantum cascade lasers and other devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If conventional epitaxial growth techniques are used to form quantum well structures, then single crystalline quality is achieved, but material combinations are restricted due to lattice constant constraints
Solution Approach 1:
The structure is segmented into two distinct parts: single-crystalline semiconductor nanomembranes for quantum wells and amorphous oxide layers for barriers. This segmentation allows each material to be optimized independently - the nanomembranes maintain single-crystalline quality while the oxide barriers provide versatile material combinations without lattice matching constraints.
Solution Approach 2:
The amorphous oxide layer acts as an intermediary between different crystalline semiconductor materials. By using transfer printing to place single-crystalline nanomembranes onto amorphous oxide barriers, the patent enables material combinations that would be impossible through direct epitaxial growth, as the amorphous layer decouples the lattice constant requirements.
2Reliability
If semiconductor-oxide quantum well structures are formed using epitaxial growth, then larger band offset is achieved, but single crystalline film formation on amorphous oxide is difficult
Solution Approach 1:
Instead of attempting to grow single-crystalline films on amorphous oxide substrates (the conventional approach), the patent inverts the process by first creating single-crystalline semiconductor nanomembranes on suitable substrates, then transferring them onto amorphous oxide barrier layers. This reversal makes single-crystalline film formation feasible while maintaining the desired semiconductor-oxide structure.
Solution Approach 2:
The single-crystalline semiconductor nanomembranes are prepared in advance on appropriate substrates using conventional epitaxial techniques, ensuring high crystalline quality before transfer. This preliminary preparation allows the nanomembranes to be formed under optimal conditions, and then transferred to the amorphous oxide barriers to create the final quantum well structure.
3Ease of manufacture
If wafer bonding is used to create semiconductor-oxide quantum wells, then structure formation is achieved, but process limitations restrict to single quantum well and poor interface sharpness
Solution Approach 1:
The patent replaces the mechanical wafer bonding process with a transfer printing approach using elastomeric stamps. This substitution enables precise control over interface formation, allows creation of multiple quantum wells in sequence, and achieves superior interface sharpness by controlling the contact and bonding conditions at the nanoscale.
Solution Approach 2:
The patent changes the bonding parameters by using room temperature or low temperature processing with elastomeric stamps, compared to the high temperature and pressure conditions of conventional wafer bonding. This parameter change enables multiple sequential bonding operations to create multi-quantum well structures while maintaining sharp interfaces and preventing unwanted atomic diffusion.
4Ease of manufacture
If conventional quantum well structures are formed with limited band offset, then epitaxial growth is feasible, but number of quantized energy levels is limited
Solution Approach 1:
The patent creates composite quantum well structures by combining single-crystalline semiconductor nanomembranes with amorphous oxide barriers. This composite approach enables the use of oxide materials with large band gaps to form high barriers, creating deep quantum wells with multiple quantized energy levels that would not be achievable with conventional semiconductor-semiconductor heterostructures.
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 fabrication of devices with deep wells and high energy barriers, overcoming lattice mismatch issues and achieving efficient carrier transport and tunneling, as demonstrated by the successful fabrication of triple-barrier superlattice structures with observed quantum tunneling effects at room temperature.
Implementation Method 1
efficient carrier transport and tunneling, as demonstrated by the successful fabrication of triple-barrier superlattice structures with observed quantum tunneling effects at room temperature
Data Source
AI summary
Superlattice structures composed of single-crystal semiconductor wells and amorphous barriers are provided. Also provided are methods for fabricating the superlattice structures and electronic, optoelectronic, and photonic devices that include the superlattice structures. The superlattice structures include alternating quantum barrier layers and quantum well layers, the quantum barrier layers comprising an amorphous inorganic material and the quantum well layers comprising a single-crystalline semiconductor.