Diamond-based Electronics Laboratory

Scientific results:

1. We have created a fundamentally new reactor type for producing a boron-doped delta-layer of a CVD diamond. For this reactor we created a special gas supply system that ensures simultaneous supply of a mixture consisting of six different gases to the reactor, as well as fast switching to another composition of the mixture and laminar flow of gases in the reaction chamber.
2. A new structure of a delta-doped conducting channel of a field transistor has been proposed and substantiated. It is based on the use of a new profile of boron concentration distribution in the channel that has two close maximums (located about 3 nm apart). It was shown that such a doping profile ensures an increased mobility and conductivity that is  60% higher than in the case of a profile that has one maximum.
3. A technology has been developed for producing strongly boron-doped layers with thicknesses of 1–2 nm with a boron concentration of (5…10) ×, 10²⁰ cm⁻³ in the process of growing a monocrystalline CVD diamond. The produced layers have a record-high hole mobility of 300 cm/V·s at a high surface concentration of charge carriers amounting to 10¹³ cm⁻². The high mobility of holes is achieved by a sharp (by 4 orders of magnitude) difference in boron concentration between a doped and an undoped diamond in the transition layer that is fractions of a nanometer wide, while the high concentration of charge carriers is achieved by complete ionization of the impurities. The proposed technology for creating  a thin electrically conducting layer in the volume of a crystal features sequential processes of growing a CVD diamond in gas mixtures with rapidly changing compositions that contain hydrogen and methane a doping impurity (boron) and a boron getter (oxygen or sulfur). The use of this technology allows to produce a diamond material with parameters suitable for creating field electronic devices on a diamond.
4. We have developed the structure of a field transistor based on a doped diamond delta-layer, including with a Schottky contact. A model of transistor with a delta-layer was built that allows to factor in various laws of changing mobility and the incompleteness ionization in various regions of the structure of the transistor. We have reviewed the influence of the depth of the delta layer on the current–voltage and capacitance–voltage characteristics of the transistor. We found a critical influence of the quality of the ohmic contact between the source and the drain on the main characteristics of a transistor.
5. The Laboratory has created a PIN diode with a high photon emission rate, about 10⁶ photons per second, from the nitrogen-doped internal region of a diode in the electroluminescence mode. Such a radiation rate was achieved by a high current density, 10³ А/cm², attained as a result of creating a diode with a strongly phosphorus-doped layer of diamond. The achieved photon emission rate allows to view diodes of such design as the basis of creating sources of individual photons radiated by NV centers in a diamond. 

Implemented results of research:

The CVD reactor created during the implementation of the project is used for conducting research within grants from the Russian Science Foundation and the Ministry of Science and Higher Education of Russia. 

Education and career development:

• On the grounds of the Laboratory and the Saint Petersburg Electrotechnical University «LETI» we organized the international research symposium «Applications of powerful microwave radiation 2014», the section «New tendencies in materials sciences» within an international conference (Nizhniy Novgorod, 2016), section meetings within the All-Russian conference «Microwave electronics and microelectronics» (Saint Petersburg, 2015).
• 17 young researchers, professionals and teachers from other organizations have completed occupational retraining at the Laboratory (JSC «Research and Production Enterprise «Istok» named after Alexander I. Shokin», Institute for Physics of Microstructures of the Russian Academy of Sciences, Volga State University of Water Transport, Lobachevkiy Nizhiny Novgorod State University, Ioffe Institute).
• One Doctor of Sciences and 5 Candidate of Sciences dissertations have been prepared and defended.
• The Laboratory has developed lecture courses for students of the Saint Petersburg Electrotechnical University «LETI» («History and methodology of nanotechnology», «Wide-band-gap diamond-like materials and devices based on them») and Lobachevkiy Nizhiny Novgorod State University («Technical foundations of plasma technologies», «Laboratory case study in a plasma physics»). We have modernized the course «Gas discharge physics».
• We have conducted lectures at the Nizhniy Novgorod Research and Education Center «Znanie–NN». 

Collaborations:

• National Institute of Standards and Technology (USA): joint research of the characteristics of samples of delta-boron-doped epitaxial layers of CVD diamond.
• Saint Petersburg Electrotechnical University «LETI» (Russia): academic cooperation.
• Kazan Scientific Center of the Russian Academy of Sciences (Russia): joint work on the topic «Research of СVD processes of growth of monocrystalline diamond containing coloring centers and interference effects in ensembles of optical centers in a diamond and (or) ceramics».