Homoepitaxial growth of CVD diamond after ICP pretreatment

Physica Rapid Research Ltrs

et al. 2016

Introduction The semiconductor single-crystal CVD diamond (ob-tained from the gas phase during homoepitaxial deposi-tion) is a wide band gap semiconductor with a gap width of 5.5 eV. CVD diamond has unique characteristics-high mobility of charge carriers, high carrier saturation speed, high electric breakdown field, the greatest thermal conductivity, high radiation and chemical resistance. On a combination of properties the CVD diamond is superior to other wide band gap semiconductors and is considered a promising material for the creation of a new generation of high-power and high-frequency electronic devices. The main difficulty in realization of the potential of CVD diamond as an electronic material is the problem of creating charge carriers inside it. Compared with conventional semiconductors, dopants in diamond have deeper energy levels that significantly impede the activation of the do-pant (the degree of ionization of the dopant at room temperature is less than 1%). Thus, in order to create an acceptable level of conductivity, it is necessary to increase the level of doping, but in case of boron doping this leads to a decrease of carriers (holes) mobility in diamond. To solve the problem of boron doping of CVD diamond, an approach based on delta-doping technology is known. A thin layer of diamond heavily doped with boron (hav-ing a thickness of 1-2 nm and concentration of boron atoms higher than 5×10 20 cm-3) is formed inside an un-doped defect-free diamond of high quality. To achieve high electronic properties (obtaining high hole mobility and conductivity of the layer), it is necessary to realize sharp boundaries between the doped and undoped materials. Recently, this problem has been successfully solved [1, 2]. This report provides an overview of the results of studies on the growth of electronic-quality epitaxial layers of diamond, the production of heavily boron-doped layers and the study of their characteristics. Experiments The novel microwave plasma assisted CVD reactor for growth of nanometric boron delta-doped layers with ultra-sharp interfaces between doped/undoped materials was built in IAPRAS [1]. Fig. 1 shows a schematic of the reactor. The main features of the reactor are: 1) rapid gas switching; 2) laminar gas flow; 3) axial symmetric resonant mode-symmetric discharge; 4) slow growth of diamond 40-100 nm/h. We achieve rapid gas switching from one input gas to another by a home-made electronic switch. The residence time of the reactor is approximately 5 s. In developed reactor the diamond deposition regimes in which one obtains thin doped delta layers with thickness of 1-2 nm with concentrations of boron about 5·10 20 cm-3 were found. Typical parameters of the delta layer under these conditions are given in Fig. 2 for the SS6-1 sample, in which the boron concentration is 4.8·10 20 cm-3 and thickness is 1 nm. Measurement of the boron concentration in the grown samples was carried out by the secondary ion mass spectroscopy (SIMS) method using a time of flight SIMS setup (IONTOF TOF.SIMS-5). T...

Section: Methodsmentioning

confidence: 99%

Nanometric diamond delta doping with boron

Butler

Vikharev

Physica Rapid Research Ltrs

et al. 2016

“…Before the growth process, substrates were mechanically polished to a surface roughness of 0.1 nm, measured with a Zygo NewView 7300 white light interferometer on an area of 0.22 × 0.22 mm 2 . To remove defects introduced by polishing from the substrate, 4–5 mm thick layer was etched away in the inductive‐coupled plasma (ICP) (Oxford Instruments, Plasmalab 80) . As a result, defect‐free substrates with an atomically smooth surface were used to grow layers of CVD diamond.…”

Section: Methodsmentioning

confidence: 99%

Investigation of Microwave Plasma during Diamond Doping by Phosphorus Using Optical Emission Spectroscopy

Lobaev

Radishev

Physica Status Solidi (a)

et al. 2019

Results of the studies of plasma-chemical processes in plasma of microwave discharge in gas mixture of hydrogen, methane, and phosphine are presented. For the first time, the dependence of emission intensity of PH radical on the parameters of plasma maintenance is studied in a wide range of variation of gas pressure, microwave power, and phosphine and methane content in gas mixture. Experiments are conducted under conditions that are used in the chemical vapor deposition (CVD) reactors for doping diamond with phosphorus. The relationship between emission intensity of PH radical and efficiency of the incorporation of phosphorus into diamond is analyzed.

“…The substrates were pre-treated by ICP plasma in order to get rid of the defects introduced during the polishing procedure [13]. ICP etching up to 5 µm etching depth did not change the surface roughness but allowed to eliminate polishing damages.…”

Section: Cvd Reactor For Diamond Delta Doping In Thismentioning

confidence: 99%

Novel microwave plasma-assisted CVD reactor for diamond delta doping

Vikharev

Phys. Status Solidi RRL

Lobaev

et al. 2016

Self Cite

We report on building a novel chemical vapor deposition (CVD) reactor for diamond delta‐doping. The main features of our reactor are: a) the use of rapid gas switching system, (b) the reactor design providing the laminar gas flow. These features provide the creation of ultra‐sharp interfaces between doped and undoped material and minimize the prolonged ”tails” formation in the doping profile. It is proved by optical emission spectroscopy that gas switching time is not more than 10 seconds. Using the novel reactor we have grown the nanometer‐thin layers of boron doped diamond. The FWHM of boron concentration profile is about 2 nm which is proved by SIMS. It is shown that the both single delta‐layer and multiple delta‐layers could be grown using the novel CVD reactor. In principle, the reactor could be used for diamond delta doping with other dopants, like nitrogen, phosphorus etc. (© 2016 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)