| Abstract: | A high current density, low contact resistance contact for wide bandgap
(WBG) or ultra-wide bandgap materials (UWBG) is disclosed. The contact is
lithographically formed so that a total perimeter length of the contact
structure is at least twice the length of the side of a contact pad
closest to the gate in a high electron mobility transistor (HEMT). The
contact structure may take the form of a plurality of columns having
various cross-sectional shapes, or may take the form of a convoluted
geometrical shape, such as a comb-like, serpentine, or spiral shape. The
depth of the contact structure permits direct contact with the
two-dimensional electron gas (2DEG) in the HEMT by the perimeter of the
contact structure. The contact structure is formed of at least one metal
layer, at least one doped material regrown layer, or at least one
implanted region. The contact structure may be applied to other WBG and
UWBG devices. |