Monocrystalline GeN Layer Formation on Nanostructured Substrates
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Solution Overview
Problem
Current methods for forming GeN layers on a Ge substrate result in either amorphous or polycrystalline structures, which are not stable at high temperatures and lack the uniformity required for advanced semiconductor applications, such as forming epitaxial layers or passivation layers.
Innovation Solution
A method involving heating a Ge substrate to between 650°C and 940°C and exposing it to a nitrogen gas flow, either N2 or NH3, while applying a plasma, to form a monocrystalline GeN layer, which is maintained during cooling to ensure stability and uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If Ge is exposed to ammonia atmosphere at high temperatures to form GeN, then GeN can be synthesized, but the GeN obtained is in powder form and does not form an epitaxial layer
Solution Approach 1:
The patent changes the physical state parameter of the Ge surface from bulk to nanostructured (nanodots or nanowires) to enable epitaxial GeN layer formation. This parameter change in the substrate morphology allows the ammonia treatment to produce crystalline layers rather than powder, resolving the contradiction between synthesis ease and manufacturing precision.
Solution Approach 2:
The patent applies preliminary nanostructuring of the Ge surface (forming nanodots or nanowires) before the ammonia exposure step. This preliminary action creates a morphology that directs the subsequent chemical reaction to form epitaxial layers, preventing powder formation and enabling precise layer growth.
2Stability of the object's composition
If GeN layers are formed by conventional methods, then GeN can be obtained, but the layers are either amorphous or polycrystalline and not stable at temperatures above 600°C
Solution Approach 1:
The patent changes the structural parameter of the GeN layer from amorphous/polycrystalline to single-crystalline by using nanostructured Ge substrates and controlled ammonia exposure. This parameter change in crystal structure directly improves thermal stability above 600°C while maintaining manufacturing precision.
Solution Approach 2:
The patent uses the Ge nanodots or nanowires as an intermediary substrate that mediates the formation of stable single-crystalline GeN layers. The nanostructured Ge acts as a template that guides the ammonia reaction to produce thermally stable crystalline GeN rather than amorphous or polycrystalline forms.
3Ease of manufacture
If Ge surface is used directly, then processing is simple, but surface states are present that require passivation
Solution Approach 1:
The patent merges the nanostructuring step with the GeN layer formation process. The same ammonia exposure that forms the GeN layer also passivates the surface states, combining two functions into one step and maintaining processing simplicity while eliminating harmful surface states.
Solution Approach 2:
The GeN layer acts as an intermediary passivation layer that protects the Ge surface from surface states. Rather than adding a separate passivation step, the GeN formation process itself creates the passivation effect, simplifying the overall process while eliminating harmful surface states.
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 method enables the formation of a stable, monocrystalline GeN layer that can be used for further semiconductor processing, such as growing group III-nitride layers and forming Ohmic or Schottky contacts with improved characteristics, and acts as a passivation layer to reduce surface states.
Implementation Method 1
exposing the substrate to a nitrogen gas flow, while heating the substrate to a temperature between 650°C and 940°C
Implementation Method 2
exposing the substrate to a nitrogen gas flow, either N2 or NH3, while applying a plasma
Data Source
Figure 1A~1C
Figure 2~3
Figure 4~5
AI summary
The present invention relates a method for forming a monocrystalline GeN layer (4) on a substrate (1) comprising at least a Ge surface (3). The method comprises, while heating the substrate (1) to a temperature between 550°C and 940°C, exposing the substrate (1 ) to a nitrogen gas flow. The present invention furthermore provides a structure comprising a monocrystalline GeN layer (4) on a substrate (1 ). The monocrystalline GeN formed by the method according to embodiments of the invention allows passivation of surface states present at the Ge surface (3).