Boron‐doped diamond layers are grown on freestanding heteroepitaxial diamond substrates by microwave plasma chemical vapor deposition (MPCVD) to verify the high potential of large‐size heteroepitaxial diamond as an ultimate semiconductor material. Due to the high crystallinity and atomically flat surface morphology of the substrate, the MPCVD‐grown boron‐doped diamond layer exhibit excellent surface properties and crystallinity, as measured by X‐ray diffraction and atomic force microscopy. The temperature‐dependent Hall effect measurements are conducted at temperature ranges between 300–800 K with cloverleaf‐shaped van der Pauw geometry. The hole concentration of boron‐doped diamond samples is between 1.1 × 1015 and 5 × 1019 cm−3 at room temperature, and the resistivity is controlled between 10−1 and 20 Ω cm by changing boron to carbon ratio. A specific contact resistance as low as 1.41 × 10−4 Ω cm2 is obtained via annealing at 500 °C. The activation energy of the boron‐doped diamond layers is reduced from 0.35 to 0.12 eV as the amount of boron dopant increases, which is attributed to the formation of impurity band. Finally, the change in the carrier mobility of boron‐doped heteroepitaxial diamond is discussed based on the scattering mechanism.
Herein, the growth of lateral‐structure p‐type diamond Schottky barrier diodes (SBDs) on a heteroepitaxial diamond substrate using a thin atomic‐layer‐deposited hafnium oxide () interfacial layer is demonstrated. The diamond SBD is grown using the microwave plasma chemical vapor deposition (MPCVD) with 1 kW microwave power at 2.45 GHz. Two kinds of samples are grown on heteroepitaxial diamond substrates under the same growth conditions for identical epi structures. And the 10 nm thickness of is used as an insulator for MIS SBD. The effects of the interlayer on the electrical properties of the SBDs are investigated using current–voltage (I–V curve) and capacitance–voltage (C–V curve) characteristics at room temperature. Compared with the metal–semiconductor (MS) SBD, the metal–insulator–semiconductor (MIS) SBD exhibited a lower reverse leakage current. The Schottky barrier height in the MIS SBD is almost 0.2 eV higher than in the MS SBD. The insertion of the interlayer reduces the inhomogeneous Schottky barrier height and enhances the barrier height because of the reduction in the interface state density.
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