Temperature-dependent model for hole transport mechanism in a poly(1.8-diaminocarbazole)/Si structure

Abstract

To investigate the conduction mechanism in an organic/inorganic heterojunction, poly(1.8-diaminocarbazole) (PDACz) on a p-type silicon substrate in a sandwich configuration were contacted with Al electrodes and temperature-dependent current–voltage measurements performed in the temperature range 280–380 K. It was found that the barrier height decreased and the ideality factor increased with decreasing temperature. Temperature and bias-dependent transition regimes were observed. These anomalies are explained by further analysis of the low- and high-field regions of the current–voltage curves. The trap density H_b and the characteristic trap energy E_t were found to be 1.85 × 10¹⁷ cm⁻³ and 25 meV, respectively. Assuming that the trapped carrier density p_t is higher than free-carrier density p, it is concluded that hole transport is dominated by space-charge-limited currents.

Keywords:

• Charge transport
• electrical properties
• organic–inorganic heterojunctions
• SCLC