For the first time, the electro-optical properties of nontetrahedrally bonded crystalline and amorphous polyphosphides have been investigated. The crystalline archetype KP15 is a high resistivity semiconductor, with photoconductivity and photoluminescence at the band gap (1.7 eV). These measurements are extended to amorphous films prepared by vapor transport methods. The resistivity of the films has been varied over eight orders of magnitude by the incorporation of 0%–2% Ni. Nonlinear metal-semiconductor behavior with good current carrying capability (1 A/cm2) has been observed. When deposited on InP, the films reduce the density of surface states in metal-insulator-semiconductor diodes to ∼1010/cm2 eV, probably by providing continuity to the group V element at the interface. It is concluded that the low crystal symmetry of polyphosphides leads to a significant new amorphous semiconductor in which the electronic coherence length is commensurate with the intermediate range order.
The equilibrium vapor pressure of phosphorus over crystalline
KP15
has been measured in the temperature range of 305°–530°C by means of a Bourdon gauge. The reaction of
6/19 KP15 false(normalsfalse)=2/19 K3P7 false(normalsfalse)+P4 false(normalgfalse)
is described by the equationlnp )(normalatm=−14,849±340T+19.35±0.5The calculated standard enthalpy and entropy of this reaction arenormalΔH2980=118.8±2.9 normalkJ/normalmol
normalΔS2980=159.0±4.2J/normalmol‐KThe standard enthalpy for the formation of
KP15
from the elemental gasesK)(normalg+15/4 P4 )(normalg=KP15 )(normalswas found to be
normalΔHnormalv,2980=−651.0±3.3 normalkJ/normalmol
. Our data show that the thermal stability of
KP15
is greater than that of crystalline red phosphorus. In addition, the kinetics of dissociation of
KP15
were found to be significantly faster than the kinetics of vaporization of crystalline red phosphorus.
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