Native defects

Stampfl C, van de Walle C G, Vogel D, Kruger P and Pollmann J 2000 Native defects and impurities in InN First-principles studies using the local-density approximation and self-interaction and relaxation-corrected pseudopotentials Phys. Rev. B 61 R7846-9... 

The Schottky barriers were excellent diodes for films annealed at 600 °C, with turn on voltages of 0.6-0.8V and minimal reverse bias leakage.48 However, many of the contacts on the as-deposited films gave large reverse bias currents and nearly ohmic responses. This behavior is indicative of degeneracy of the semiconductor because of a high carrier density resulting from native defects. The improvement in the diode behavior of the annealed films is attributed to enhanced crystallinity and reduction of defects. 

In the fluorides, chlorides and oxides of the Group-A main-group metals and the transition metals zirconium and hafnium, aliovalent cation substitutions are generally charge-compensated by the introduction of native defects (e.g. an oxygen vacancy in Zr, ,Ca 02 x) because the intrinsic is large however, in some oxides neutral oxygen or water may... 

The main effect of the surface treatment is the removal of the native defect containing surface on the fibers. This surface layer itself can not sustain any great degree of... 

Fig. 14. The interfacial shear strength versus surface oxygen concentration for the A and HM carbon fibers. The large increase from the untreated (U) case to the surface treated case (S) for both fibers is due to removal of the native defect surface layer plus the addition of surface chemical groups. Removal of the surface groups with various treatments indicates that the surface chemical effect was a minor part of the overall increase. From Drzal et al.751...

Theoretical estimates of the heats and entropies of formation of vacancies correspond well with those of the native defects observed in diffusion and quenching experiments (15,17-19). 

After the balance sheet of pros and cons surrounding the question of the native defect in Si is reviewed, the question remains. What is the native defect responsible for the diffusion of impurity and growth of defects in Si So far we only have clues. 

The doping of a solid is similar to the enhancement of the H30+ or OH- concentration in water by adding a strong acid or base. However, while in water mobilities of dopant ions are frequently similar to those of the native defects H30+ and OH-[69, 70], dopant ions in solids (e.g. CdXg in AgCl) are almost immobile. This is also why supporting electrolytes (i.e. electrolytes with dissolved dopants that enhance the ionic conductivity, but do not influence electrochemical electrode reactions [71, 72], are unknown in solid state electrochemistry. 

The other application of the LP measurements is to evaluate strains in the heteroepitaxial layers and/or native defect and dopant content. The latter application has not been explored for nitrides yet. 

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