Abstract: . . .  extrapolating a plot of sheet charge concen- tration versus film thickness to zero thickness [7,12]. Mg- doped InN has an electron accumulation layer similar to undoped films at the surface, but also, uniquely, has a charge depletion layer and then a region of negative space charge (as evidenced by a change in the sign of @ ? C ÿ2 ? @V ) that is attributed to ionized shallow acceptors. From the net concentration of ionized acceptors, we infer a bulk Mg doping level in the low-10 19 cm ÿ3  . . .
. . .  U.S. Department of Energy under Contract No. DE-AC02- 05CH11231. The work at Cornell University is supported by ONR under Contract No. N000149910936. One of the authors (R.E. J.) thanks the U.S. Department of Defense for current support and the National Science Foundation for previous support. [1] V. Yu. Davydov et al. , Phys. Status Solidi B 229 , R1 (2002). [2] J. Wu et al. , Appl. Phys. Lett. 80 , 3967 (2002). [3] W. Walukiewicz, Physica (Amsterdam) 302B , 123 (2001). [4] H. Obloh et al. , J. Cryst. Growth 195 , 270 (1998).  . . .
. . .  measurements, transport measurements of as-grown and He ? -irradiated films, and photoluminescence spectroscopy are consistent with our model. Theoretical calculations demonstrating satisfactory modeling of these results pro- vide further support. While the quantitative p -type con- ductivity of the bulk material remains to be evaluated, the achievement of a net concentration of ionized acceptors in InN is a major step toward the fabrication of p - n junctions, and therefore electronic and optoelectronic devices using InN. This work is . . .
. . .  buffer layer, but this has not been proven. It should be noted that the electrolyte-based CV technique causes the ionization of all uncompensated acceptors in the film, which is not necessarily the concen- tration that is ionized at room temperature. Thus, the inferred bulk doping level may not indicate the concentra- tion of free holes. The sheet concentrations of free electrons in the Mg- doped samples, as determined from Hall effect measure- ments, range from 5 10 13 to 7 10 14 cm ÿ2 , and elec- . . .
. . .  While the quantitative p -type con- ductivity of the bulk material remains to be evaluated, the achievement of a net concentration of ionized acceptors in InN is a major step toward the fabrication of p - n junctions, and therefore electronic and optoelectronic devices using InN. This work is supported by the Director, Office of Science, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering, of the U.S. Department of Energy under Contract No. DE-AC02- 05CH11231. The work at Cornell University is supported by ONR under . . .
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