CVD reactor and method for nanometric delta doping of diamond

Abstract

An apparatus and method for creating nanometric delta doped layers in epitaxial diamond includes providing a dummy gas load with gas impedance equivalent to the reactor, and switching gas supplied between the reactor and the gas dummy load without stopping either flow, thereby enabling rapid flow and rapid gas switching without turbulence. An atomically smooth, undamaged substrate can be prepared, preferably in the (100) plane, by etching the surface after polishing to remove subsurface damage. A gas phase chemical getter reactant such as hydrogen disulfide can be used to suppress incorporation of residual boron into the intrinsic layers. Embodiments can produce interfaces between doped and mobile layers that provide at least 100 cm2 / Vsec carrier mobility and 1013 cm−2 sheet carrier concentration.

Description

FIELD OF THE INVENTION[0001]The invention relates to reactors and methods for epitaxial growth of diamond, and more particularly to chemical vapor deposition (“CVD”) reactors and methods for creating nanometric delta doped layers in epitaxially grown single crystals of diamond.BACKGROUND OF THE INVENTION[0002]Diamond is of strong interest as a potential semiconductor material for high voltage, high frequency, and / or high power active and passive electronic devices because of its superlative materials properties, including high electronic carrier mobilities, high breakdown field strength, high thermal diffusivity, favorable matrix for quantum devices, as well as many other desirable optical, chemical, and materials properties. However, a major barrier to exploiting diamond for active electronic applications is that there are no dopants known that have a sufficiently low thermal activation energy barrier to create a concentration of electronic carriers and a carrier mobility in diamon...

AI Technical Summary

Benefits of technology

The patent describes a way to create very smooth and abrupt layers in human-made diamond using a special gas supply that minimizes turbulence and mixing. The method includes polishing the surface of the diamond and then etching it to remove any damage. This results in a very smooth and damage-free surface for the epitaxial deposition of a delta doping layer that has very high carrier mobility and sheet carrier concentrations. Embodiments of the patent describe preparing the diamond substrate for deposition by maintaining rapid gas flows while using extraordinarily slow growth rates.

Problems solved by technology

However, a major barrier to exploiting diamond for active electronic applications is that there are no dopants known that have a sufficiently low thermal activation energy barrier to create a concentration of electronic carriers and a carrier mobility in diamond at room temperature that is adequate for most devices of interest.

However, this activation energy is still high enough to ensure that only a fraction of the boron present is activated at room temperature, leading to relatively low concentrations of free carriers.

Unfortunately, as the activation energy of the holes decreases, so does carrier mobility, not only because of the increased impurity scattering but also due to the onset of a low-mobility, hopping-like conduction.

Recent attempts at delta doping of diamond with boron have failed to demonstrate the theoretically expected performance, and have shown low carrier mobilities, low sheet carrier concentrations, and / or low channel mobility.

Some of these studies have attributed this disappointing performance to poor lateral homogeneity and interrupted morphology of the delta layers.

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