  Diamond and many newly emerged semiconductor materials show outstanding
optical and magnetic properties. However, they cannot be as efficiently doped
as silicon or gallium arsenide, which limits their practical applicability.
Here, we report a superinjection effect in diamond p-i-n diodes, which gives
the possibility to inject orders of magnitude more electrons into the i-region
of the diode than the doping of the n-type injection layer allows. Moreover, we
show that the efficiency of electron injection can be further improved using an
i-p grating implemented in the i-region. The predicted superinjection effect
enables to overcome fundamental limitations related to the high activation
energy of donors in diamond and gives the possibility to design
high-performance devices.
