Influence of crystal polarity and metal electronegativity on the sensing properties of III-nitrides ∗

The potentiometric response to different anions and pH, of a non-polar a-plane GaN crystal is examined for first time, and it is compared with that obtained from two polar III-N materials, +c-plane GaN and +c-plane InN. The obtained results reveal that the polar InN is superior for anionic sensing applications, while the polar GaN is more suitable for pH sensing. Interestingly, the non-polar GaN shows a potentiometric response to the zwitterionic MES compound that bears both a Lewis basic and a Lewis acidic moiety on its structure, and thus it seems promising for sensing substances of this kind.