How does the miracle element boron enhance the semiconductor properties of diamond?

Diamond is a structure of carbon. In a diamond crystal, each carbon atom has 4 nearest neighboring carbon atoms and 12 next neighboring carbon atoms. There are 8 atoms in a unit cube. As the radius of boron atoms is smaller than that of carbon atoms, it is easy to enter the diamond crystal lattice. There are three possible forms of boron in diamond crystals: one is that boron atoms take the place of carbon atoms; the second is that boron atoms are located in between carbon atoms; and the third is that boron atoms also fill the defects appearing in the growth process of diamond crystals, especially surface defects, and they all have an effect on the performance of diamond crystals.

Boron in diamond crystals can be added by means of boron or borides. Due to the introduction of boron atoms, the oxidation resistance, electrical conductivity, chemical affection and mechanical properties of diamond are significantly changed. The boron content in B-doped single crystal diamond is generally very low, but the effect on improving and enhancing the properties of diamond crystals is significant, especially in the semiconductor properties.

For pure diamond, because it is not free to move inside the electron and has a 5.5ev wide forbidden band, so the resistivity is very high, can be used as a good electrical insulator; However, when the diamond doped into the Ⅲ or Ⅴ elements, diamond can be transformed into a semiconductor or even a conductor from the insulator. With three valence electrons of boron atoms into the diamond lattice will replace the carbon atom in the form of substitution to become the main center, the lattice produces hole carriers, diamond becomes a hole semiconductor, this doping is called P-type doping. With the increase of boron content, the conductivity of diamond increases.

B-doped single crystal diamond is the material of choice for the preparation of high temperature, high power semiconductor components, and has broad application prospects in the fields of electronics, nuclear energy and aerospace. At present, further research should be done in diamond boron doping to improve the carrier mobility of boron doped diamond by choosing suitable boron sources and adjusting the doping concentration of boron, etc., and apply it to the preparation of diodes, field effect transistors and detectors during the period to improve the working performance of the devices.

CSMH uses the MPCVD method to prepare large-sized and high-quality diamonds, and currently has mature products such as diamond heat sinks, diamond wafers, diamond windows, diamond heterojunction integrated composite substrates, etc. Among them, the thermal conductivity of diamond heat sinks is 1000-2200W/(m.k), and the surface roughness of diamond wafer Ra<1nm. It has been applied in aerospace, high-power semiconductor lasers, optical communication, chip heat dissipation, nuclear fusion and other fields.