Investigation of the importance of interface and bulk limited transport mechanisms on the leakage current of high dielectric constant thin film capacitors

Abstract

The importance of interface and bulk transport mechanisms on the leakage current of high dielectric constant thin film capacitors is examined by deriving an equation for the J–VA characteristic of a capacitor that includes the transport mechanisms of thermionic emission (TE), thermionic field emission (TFE), and carrier drift–diffusion (DD). The current is controlled by the slowest of three effective velocity parameters v1md, vD, and ṽ2dm characterizing electron injection into the dielectric at the cathode by TE and TFE, carrier DD in the film bulk, and electron ejection from the dielectric at the anode by TE and TFE, respectively. The effective velocity parameters are evaluated for a Pt/BST/Pt thin film capacitor that has been exposed to forming gas and it is shown that the dominant transport mechanism is interface limited TFE from the cathode with negligible influence of carrier transport by DD in the film bulk. Implications of these results on existing transport calculations for high dielectric constant thin film capacitors are discussed.

Tunneling in sub-5nm La2O3 films deposited by E-beam evaporation

“…To our knowledge, no report exists concerning the simulation of the direct and Fowler-Nordheim regimes in such material. Of course, several works have faced the problem of the tunneling current in high-K dielectrics from the theoretical point of view [20][21][22], but these approaches often require mathematical developments and/or detailed knowledge of the tunneling structure that prevent their use for practical purposes. Apart from the fact that the applicability of the WKB method in ultrathin high-K oxides, used to derive Eqs.…”

Metal-ferroelectric-metal heterostructures with Schottky contacts. I. Influence of the ferroelectric properties

“…Second, both static and dynamic dielectric constants occur in (16). Compared with the classical case of semiconductors, when the difference between the static and the dynamic dielectric constant is not too large, in the case of ferroelectrics the dynamic dielectric constants is very low compared to the static value.…”

“…The charge concentration extracted from the C-V characteristic is the concentration of free carriers at the given temperature, and not the effective fixe charge N eff in SCR. Therefore, from the C-V measurements p(T) occurring in (6) is in fact calculated, whereas the major role in transport mechanism is plaid by N eff , occurring in (8) and (16). Parenthetically it has to be noted that the free carrier concentration is controlled by the deep level if it pins the Fermi level.…”

“…Screening the vast literature on this topic [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] the transport mechanisms can be grouped in two major categories: i) interface controlled mechanisms based on Schottky emission or Fowler-Nordheim tunneling and ii) bulk controlled mechanisms such as ohmic, space charge limited currents, Pool-Frenkel emission, ionic conduction, or a combination of them. However, the main dilemma arises from the question whatever the ferroelectric film should be treated as an insulator or as a semiconductor.…”

Resistive switching mechanism of TiO2 thin films grown by atomic-layer deposition

“…The higher emission or tunneling leakage current through an insulating film implies that the point defect density is higher. 19,20 This suggests the following mechanism for resistive switching; when a high voltage is applied to the TiO 2 film, many point defects ͑probably oxygen vacancies͒ are formed and at a certain voltage ͑V on ͒ these defects gather together to form the extended defects ͑conducting filaments͒. It is also considered that several noncomplete filaments ͑not extended throughout the whole film thickness͒ are formed in the nonconducting area and that they contribute to the leakage current.…”