Current–voltage characteristics and impedance spectroscopy of LiNbO3 films grown by RF magnetron sputtering

Abstract

Polycrystalline LiNbO 3 films with random orientation of grains on (001)Si substrates have been grown by RF magnetron sputtering method. Electrical conductance of the formed (001)Si-LiNbO 3 heterostructures is defined through hopping mechanism by charge localization centers (CLC) in the band gap of LiNbO 3 with concentration N t = 2.3 9 10 24 m -3 . Analysis of the impedance frequency spectrum has disclosed two relaxation processes of Maxwell-Wagner type with relaxation times s 1 = 0.1 s and s 2 = 1 9 10 -4 s. Thermal annealing at T = 650°C leads to an increase in the average grain size from 50 to 95 nm; it also leads to a decrease in the CLC concentration down to N t = 2.8 9 10 20 m -3 . Electrical conductance of (001)Si-LiNbO 3 heterostructures after thermal annealing is determined by space charge limited conduction mechanism. There have been defined parameters of dielectric hysteresis loops. It has been demonstrated that thermal annealing leads to a decrease in values of remanent polarization and coercive field.

Influence Sputtering Conditions on Electrical Characteristics of Si-LiNbO3Heterostructures Formed by Radio-Frequency Magnetron Sputtering

“…Extrapolating the value V o when T→0 (see Fig. 8 As has been mentioned above, field emission affects conductivity in sample LN133 and such type of charge transport called nonactivation hopping conduction was revealed in our work [12]. In this case I-V characteristics obey the following expression:…”

“…Based on the methods of C-V analysis, we derived the following value for the positive effective fixed charge: Q ef = 2·10 −7 Q/cm 2 and Q ef = 8·10 −7 Q/cm 2 for LN133 and LN134, respectively. It is important to emphasize that the sign of this charge did not depend on substrate type and was the same for LiNbO 3 films grown on both p-type and n-type silicon substrates [7,12].…”

“…Also, hopping distance and effective defect concentration can be calculated using the following expressions [12]:…”

“…Various techniques are applied for creating thin LiNbO 3 films on different substrates: sol-gel method [1], pulsed laser deposition [2], liquid-phase epitaxy [3], and chemical vapor deposition from vapor phase (CVD process) [4]. Radio-frequency (RF) magnetron sputtering (RFMS) being an effective vacuum method allows preservation of the initial elemental composition of grown complex oxides [5][6][7] bulk properties of LiNbO 3 as well as barrier conditions at the Si-LiNbO 3 interface [11,12] and separation of these types of influence is an important issue. In general, barrier conditions at the heterointerface depend on many factors: electron affinities of contacting materials, interface states, built-in charge, etc.…”

Electrical properties and local domain structure of LiNbO3 thin film grown by ion beam sputtering method

“…With the approach presented in Ref. [16] where it has been emphasized that electrical properties of the (001)Si-LiNbO 3 heterostructures largely depend on the LiNbO 3 layer as our basis, we have described the impedance spectra using the electrical equivalent circuit shown in Fig. 2(a) (see insert).…”