Abstract:
Thin films of wide band-gap semiconductors are deposited by the pulsed laser deposition method. Optimal deposition parameters for the individual compounds are reported. A family of p-type BaCuQF (Q = S, Se, Te) ceramics with a layered crystalline structure is investigated for active and passive device applications.
Epitaxial films of BaCuTeF are grown in-situ on single-crystal MgO substrates. These films exhibit a maximum hole mobility of 8 cm²/Vs and conductivity of 167 S/cm.
The band gap of BaCuTeF is 3 eV, much higher than 2.3 eV expected from powder results. BaCuSeF textured films are also grown on MgO substrates with a lower 1.5 cm²/Vs and 1.7 x 10¹⁸ cm⁻³ carrier concentration. Crystalline films of BaCuSF are obtained by post-annealing in H₂S and Ar gases. Excitonic absorptions above 3 eV in BaCuSeF and BaCuSF indicate the upper limit of photon transmission. Various photoluminescence colors in the visible range are observed under UV excitation. The
Zn₂In₂O₅ (ZIO) is also a layered semiconductor, but with electron majority carrier-type. Amorphous and crystalline ZIO films have 2 x 10³ S/cm conductivity and indirect band gaps between 2.8 and 3.2 eV, respectively. The amorphous phase is stable to high temperature exposure up to 500˚C.
