Electrical Transport Properties of GalnN and AlInN

Compositional inhomogeneities in InGaN are often underlined see for example [4], Immiscibility of InN in a nitride alloy is very strong and InN microscopic inclusions as well as metallic In are found in the specimens grown currently. Although no studies of ensuing transport properties were made, analogies with other precipitated semiconductor materials point to possible influences on both mobility and carrier concentration. 

Transport data in In AIN are extremely scarce. Kubota et al [5] reported that films with large In fraction are conductive and those with large Al fraction are resistive, in close analogy to the parent compounds InN and AIN. 

Contacts to AlInN were examined in [6]. Titanium and aluminium metallisations exhibited ohmic behaviour and their thermal stability was evaluated. InN-based ohmic contacts were examined also by Donovan et al [7], The use of sapphire substrates combined with growth temperatures in the vicinity of 575°C produced acceptable contact resistances in the range of 10 6 Q cm2. 

FIGURE 1 Calculated electron drift mobilities at 300 K in GalnN and AlInN as a function of composition, in the limit of negligible ionised impurity scattering, after [8], 

Nitrides Symposium Boston, MA, USA, 2-6 December 1996, Ed. F.A. Ponce (Materials Research Society, Pittsburgh, PA, USA, 1997) p.l 143 ] 

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