A new method for judging ohmic contact quality of metal/thin semiconductor layer
circular transmission line model extrapolation method in the ring
is developed.The mesa isolation is omitted
thus simplifying sample preparation.Because all the measurements are located in the ring
there is no need to consider the effects of any boundary out side the ring.Lateral current crowding effect are completely eliminated because of the symmetrical construction of the disc and concentric ring.The straight line is fitted by measurement values