TRANSPORT-PROPERTIES OF THIN CD3AS2 POLYCRYSTALLINE FILMS

Structural investigation shows that all Cd3As2 thin films, whatever th eir film thickness in the range of 50.5-200 nm and whatever their depo sition rate up to 5 nm s(-1), have a polycrystalline nature and a tetr agonal structure belonging to the alpha-phase. Dark electrical resisti vity p, Hall coefficient R(H) and Seebeck coefficient S measurements i ndicate that Cd3As2 films in polycrystalline form behave as a degenera te semiconductor. The sign of both R(H) and S shows that these films a re n-type semiconductors. The Seebeck coefficient measurements lead to the existing conduction mechanisms as they show throughout the graphi cal representation of S vs 1000/T that there are two different mechani sms which are the ionized scattering mechanism (predominant at lower t emperature range up to 150 K) and lattice scattering mechanism (predom inant at relatively higher temperatures, i.e. above 250 K). The graphi cal representation of S vs 1000/T was used in conjunction with the opt ical energy gap of Cd3As2 films in polycrystalline form to show that m u n > mu p which is characteristic of most semiconducting materials. T he electron concentration calculated from R(H) in conjunction with the reduced Fermi energy calculated from S was used to determine the elec tron effective mass m of Cd3As2 crystalline thin films. it was found that m = 0.053 m(0).