ELECTRONIC-PROPERTIES OF EVAPORATED THIN-FILMS OF BIS(1,2-BENZOQUINONE DIOXIMATO)METAL(II), M(BQD)(2) (M=NI, PD AND PT)

Thin films of bis(1,2-benzoquinone dioximato)metal(II), M(bqd)(2), whe re the metal(II) or M is Ni, Pd or Pt, gives a divalent d(8) metal ion , have been prepared by evaporation onto a quartz or a glass substrate held at room temperature in a Vacuum (ca. 1.33 x 10(-4) Pa). X-Ray di ffraction profiles, electronic absorption spectra, UV photoelectron sp ectra and electrical resistivities of these complex thin films have be en measured to study the characteristics of their electronic propertie s. The lowest absorption bands of the three kinds of complex films wer e observed at about 0.99, 1.93 and 1.49 eV for Pt(bqd)(2), Pd(bqd)(2) and Ni(bqd)(2), respectively. Those bands for Pt(bqd)(2) and Pd(bqd)(2 ) were assigned to the electronic transitions from the levels nd(z)2 t o (n + 1 )p(z) (n = 4 and 5). The threshold ionization energies of the thin films were 4.96, 5.31 and 5.23 eV for Pt(bqd)(2), Pd(bqd)(2) and Ni(bqd)(2), respectively. The magnitudes of both energy values are in the order Pd > Ni > Pt for M in M(bqd)(2). The electrical resistivity of the thin film of Pt(bqd)(2) was measured to be 6.3 x 10(4) Omega c m with a thermal energy gap of 0.34 eV, which was obtained from the ac tivation energy for its electric conduction in the temperature range f rom 140 K to room temperature. On the other hand, the energy gap of Pt (bqd)(2) was estimated to be Delta epsilon = 0.84 eV from the energy d iagram derived for its external photoelectric process an the basis of the band model for an intrinsic semiconductor.