The physical mechanism of the current flow in Pd-(heavily doped p-AlxGa1-xN
) ohmic contact is studied. Chloride-hydride epitaxy was used to grow the p
-Al0.06Ga0.94N solid solution with uncompensated acceptor concentration N-a
- N-d ranging from 3 x 10(18) up to 10(19) cm(-3). Thermal vacuum depositi
on and subsequent thermal treatment were used to form an ohmic Pd contact.
It is shown that, after the thermal treatment, the Pd-p-Al0.06Ga0.94N barri
er contact with a potential barrier height of about 2.3 V becomes ohmic and
the barrier height decreases to approximately 0.05 V. For uncompensated ac
ceptor concentration N-a - N-d = 3 x 10(18) cm(-3), thermionic emission is
found to be the main mechanism of the current through the Pd-p-Al0.06Ga0.94
N ohmic contact. An increase in N-a - N-d to approximately 10(19) cm(-3) in
the solid solution leads to a transition from thermionic emission (at high
temperatures) to tunneling (at low temperatures). (C) 2001 MAIK "Nauka/Int
erperiodica".