Low-frequency noise and current–voltage characteristics of Schottky barrier contacts in a wide temperature range

Abstract

Articles you may be interested inExtraction of Schottky diode parameters from current-voltage data for a chemical-vapor-deposited diamond/silicon structure over a wide temperature rangeThe low-frequency (1/f ) noise and current-voltage characteristics of GaAs and Si Schottky barrier diodes are studied over a wide temperature range: 77-400 K. The peculiarities of temperature and current dependences of the spectral intensity ͑SI͒ of current fluctuations S i (I,T) ͑a specific increase of the SI with decrease in temperature and a deviation from a quadratic dependence of the S i -I 2 form͒ are explained adequately by the influence of a predominantly local barrier height lowering at a Schottky barrier contact ͑SBC͒, most likely at its periphery. The Gaussian barrier height distribution at SBCs does not explain these peculiarities. It is shown that the 1/f noise at SBCs approaches the ''ideal'' noise of the S i -I ␤ / f ␣ form, where ␤ϭ2 and ␣ϭ1, as the temperature increases. The explanation for the ''low-temperature anomaly'' in SBCs ͓an increase in the ideality factor n and a decrease in the measured ͑from a saturation current͒ barrier height bm with decrease in temperature, a weak variation of their product bn ϵn bm in this case, and the character of the temperature dependence n(T) in the form of nХ1ϩT 0 /T ͑''T 0 effect''͔͒ is presented. This explanation is based on a fundamental property of real SBCs-the nonlinear bias dependence of the barrier height resulting in a growth of the ideality factor with a bias voltage ͑current͒ increase. The other necessary condition for revealing the ''low-temperature anomaly'' is the inclusion in theory of the fact that the n and bm measurements are performed at the same current for all temperatures. An expression for the flatband barrier height b f is derived. It takes into account the nonlinear bias dependence of the barrier height and the n(I) dependence which follows from it. On the basis of this expression the conditions are defined at which a simple approximation for b f is valid: b f Х bn ϵn bm .

Analysis of the actual Schottky-barrier contact model in a wide temperature and bias-voltage range

“…(6) permits one to calculate the quantities ϕ bn ≡ nϕ bm and ϕ bm , examine their temperature dependences for a given current, and compare the measured barrier height ϕ bm and the quantity ϕ bn with the actual (true) barrier height ϕ bI in a temperature range. Equation (5) gives similar possibilities for comparing the values of ϕ b (V ), ϕ bn , and ϕ bm in a range of biases for a given temperature. Finally, Eq.…”

“…By manipulating these parameters, one can obtain a broad variety of the presented characteristics (see Fig. 3a), which is typical of the actual MSSBCs [5]. As also follows from the calculation (see Sec.…”

“…Here, I bf = AR * T 2 exp[−qϕ s /(kT )] is the flat-band current corresponding, as follows from Eq. (1), to the flat-band bias V = V bf and I bfa is the effective (apparent) flat-band current introduced in [4] (see also [5]). It is shown in those papers that the latter quantity is a function of the chosen tangency point and can, in principle, be determined experimentally.…”

“…A combination of these values, as well as the parameters N 0 s and E 0 of the surface electron state distribution, were chosen on the basis of the known data for GaAs-and Si-based metal-semiconductor contacts [1, 2] and mainly from the qualitative agreement between the calculated data and the widely known experimental values of the ideality factor of the I − V characteristic, the measured barrier height, and their temperature dependences for the GaAs-and Si-based Schottky-barrier diodes (see, e.g., [5]). The temperature dependences were calculated for the current I = 10 −5 A.…”

“…A considerable number of papers have been devoted to explaining the effects detected in a metalsemiconductor Schottky-barrier contact (see references in [4]), but the most general interpretation of the nature of the low-temperature anomaly in actual Schottky-barrier diodes and related issues concerning the actual, measured, and flat-band barrier heights was for the first time given in [4,5]. The arguments are based on the view that the nonlinear dependence of the Schottky-barrier height on the bias leads to an increase in the ideality factor of the I − V characteristic with increasing bias and on allowance for the condition, which is virtually satisfied in the experiment, that the current be constant when the barrier height and the ideality factor of the I − V characteristic are determined in a temperature range.…”