Analytical studies on multiple delta doping in diamond thin films for efficient hole excitation and conductivity enhancement

Beneficial features of boron multiple delta doping (MDD) in synthetic diamond thin films are studied analytically and compared with MDD in GaAs. In spite of a deep boron level (∼0.3 eV), MDD greatly helps the thermal excitation of holes via elevation of the Fermi level toward the acceptor boron level. Thus, a hole excitation 6-7 times higher than that of the uniformly doped one is obtained. Furthermore, more than 90% of holes are in the spacer layer (i-diamond) where the mobility is high, resulting in a film conductance of the MDD structure more than 20 times higher than that of the conventional one when the same amount of boron is uniformly doped.