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Role of the valence band structure in the statistics and electrical conductivity in p-GaN

The valence band of p-GaN has non-trivial structure close to the center of the Brillouin zone. Since three E(K) surfaces are closely spaced they should be all taken into account. First we analyze the influence of the effective masses on the hole statistics. As the result we demonstrate that frequently used expression p=Nv*exp[-(EF-Ev)/kT] is not accurate for p-GaN. Corrected expression is presented for the examination of the hole concentration dependence on relevant parameters. Considering the transport properties, we discuss the consequences of the anisotropy of the effective mass on the electrical conductivity. This is significant since the &#8216 ; horizontal&#8217 ; conductivity is the parameter that is routinely measured while the &#8216 ; vertical&#8217 ; (c-axis) conductivity is important in all opto-electronic devices. For example, the hole concentration, as determined from the Hall-constant measurement is compared to the hole concentration that is relevant for &#8216 ; vertical&#8217 ; conductivity. In addition, we also analyze the influence of strain on the statistical and transport properties of the free holes in p-GaN.

GaN; hole; condictivity

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