Controlled n-doping of GaAs on Si(111) via Periodic Arsenic Flux
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Solution Overview
Problem
The challenge of achieving controlled n-doping of group III-V materials grown on (111) Si substrates is exacerbated by non-intentional doping, which can lead to p-type semiconductor formation, making it difficult to obtain n-type semiconductors through compensation doping, especially when p-doping concentrations are high.
Innovation Solution
A method involving continuous arsenic flux concentration during molecular beam epitaxy growth, with a nucleation layer of group III-Sb materials, alternating growth and no-growth steps, and maintaining a temperature between 300° C. to 580° C., to achieve a p-type doping concentration of 2E14 cm−3 to 3.6E16 cm−3 and mobility ≥1.6E3 cm2/Vs, enabling compensation doping with a n-doping agent.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If non-intentional doping occurs during MBE growth, then p-type semiconductor formation occurs, but controlled n-doping becomes difficult or impossible
Solution Approach 1:
The patent applies preliminary action by growing a nucleation layer of group III-Sb material before the main GaAs growth. This nucleation layer is grown under specific conditions (Sb flux, then Ga flux) to prepare the substrate surface in advance, ensuring that subsequent GaAs growth occurs on a pre-conditioned surface that reduces non-intentional p-doping and enables better control over n-doping through the alternating flux method
Solution Approach 2:
The patent implements periodic action through alternating growth steps and no-growth steps during GaAs deposition. During growth steps, both Ga and As fluxes are supplied; during no-growth steps, only As flux is supplied while Ga flux is interrupted. This periodic alternation maintains a constant As flux concentration throughout, preventing Ga-rich conditions that cause non-intentional p-doping while enabling controlled n-doping
2Reliability
If high p-doping concentration is present, then compensation doping becomes less effective, but achieving n-type semiconductor remains necessary
Solution Approach 1:
The nucleation layer growth is performed in advance to prepare the substrate surface with optimal properties before main GaAs growth. This preliminary step ensures that the subsequent GaAs layer grows on a surface that minimizes non-intentional p-doping, thereby improving the effectiveness of compensation doping and enabling n-type semiconductor formation even when some p-doping is present
Solution Approach 2:
The patent maintains continuous As flux throughout the entire growth process, including during no-growth steps where Ga flux is interrupted. This continuity of As supply ensures constant As flux concentration, preventing Ga-rich conditions that would increase non-intentional p-doping and maintain conditions favorable for successful compensation doping and n-type semiconductor formation
3Manufacturing precision
If alternating growth and no-growth steps are used, then n-doping control is improved, but growth time increases
Solution Approach 1:
The patent uses periodic alternation between growth steps (both Ga and As flux supplied) and no-growth steps (As flux only, Ga flux interrupted) to maintain constant As flux concentration. This periodic action enables precise control over n-doping by preventing Ga-rich conditions while still achieving complete GaAs layer formation over the total growth cycle
Solution Approach 2:
The patent changes the flux parameters dynamically during growth - specifically interrupting Ga flux during no-growth steps while maintaining As flux. This parameter change (from both fluxes on to As flux only) enables precise control over doping conditions without requiring complete interruption of the growth process, balancing doping control precision with reasonable growth time
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 allows for controlled n-doping of GaAs on Si(111), ensuring a net n-type doping with sufficient mobility and carrier concentration, facilitating the production of n-type semiconductors and reducing ohmic resistance.
Implementation Method 1
directing a continually flowing arsenic flux towards the growth interface of the (111)Si substrate
Implementation Method 2
A method of controllable n-doping in a molecular beam epitaxy (MBE) growth process comprising growing group III-V materials on a (111)Si substrate
Data Source
AI summary
The present invention is related to a method of providing n-doped group III-V materials grown on (111) Si, and especially to a method comprising steps of growth of group III-V materials interleaved with steps of no growth, wherein both growth steps and no growth steps are subject to a constant uninterrupted arsenic flux concentration.