Abstract
The effects of photoadsorbed H2, N2, O2 and Ar on the photoluminescence (PL) of ZnSe nanowires are studied. Thenanowires were grown by metalorganic chemical vapour deposition. Passivationand cleaning by photodesorption in vacuum serve to sensitize the surface ofthe nanowires to adsorbed gases. The PL intensity of the near band edgeemissions is enhanced after each sensitizing step. When different gases arephotoadsorbed, different responses in the intensity are observed; it increases forH2 while itdecreases for N2, O2 and Ar. While the effects of other gases can be reversed by photodesorption, that ofO2 cannot. Once oxidized, the nanowires are no longer sensitive to the ambient gases. Onlyabove band gap photons are found to induce the adsorption, desorption and oxidation,below band gap photons are found to be ineffective. The results are understood from apicture of surface states and band bending and may form the basis of using nanowires tofabricate re-useable, multi-gas sensors.
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