This paper proposes and examines three different plots for the determination of the saturation current, the ideality factor, and the series resistance of Schottky diodes and solar cells from the measurement of a single current (I)/voltage(V) curve. All three plots utilize the small signal conductance and avoid the traditional Norde plot completely. A test reveals that the series resistance and the barrier height of a test diode can be determined with an accuracy of better than 1%. Finally it is shown that a numerical agreement between measured and fittedI/V curves is generally insufficient to prove the physical validity of current transport models.

Schottky barrier and pn-junction I/V plots — Small signal evaluation

A simple analytical expression is presented for the current flow in a diode driven by a voltage source through a series resistance. The proposed solution is based on the Lambert W-function. The new expression leads to an efficient method for extracting series resistance from measured current-voltage data. Experimental results are presented which validate the proposed solution and extraction method.

Exact analytical solution for current flow through diode with series resistance

An extended Norde plot is described which makes it possible to determine the series resistance, barrier height, and ideality factor from one I‐V measurement of a Schottky barrier diode. A theoretical derivation is performed followed with experimental data, which demonstrates the feasibility of the method.

Generalized Norde plot including determination of the ideality factor

A surface plasmon polariton detector is demonstrated at infra-red wavelengths. The device consists of a metal stripe on silicon forming a Schottky contact thereon and supporting surface a plasmon polariton mode that is strongly confined and localised to the metal–semiconductor interface. Detection of optical radiation below the bandgap of silicon (at infrared wavelengths) occurs through internal photoemission. Responsivities of 0.38 and 1.04 mA/W were measured via end-fire coupling to a tapered optical fibre, at room temperature and at a wavelength of 1280 nm, for gold and aluminium stripes on n-type silicon, respectively. The device can be integrated with other structures used in nano-plasmonics, nano-photonics or silicon-based photonics, and it holds promise for short-reach optical interconnects and power monitoring applications.

Surface plasmon waveguide Schottky detector.

I–V Measurements on PtSi-Si Schottky structures in a wide temperature range from 90 to 350 K were carried out. The contributions of thermionic-emission current and various other current-transport mechanisms were assumed when evaluating the Schottky barrier height Φ0. Thus the generation-recombination, tunneling and leak currents caused by inhomogeneities and defects at the metal-semiconductor interface were taken into account.

Taking the above-mentioned mechanisms and their temperature dependence into consideration in the Schottky diode model, an outstanding agreement between theory and experiment was achieved in a wide temperature range.

Excluding the secondary current-transport mechanisms from the total current, a more exact value of the thermionic-emission saturation current Ite and thus a more accurate value ofΦb was reached.

The barrier height Φb and the modified Richardson constant A∗∗ were calculated from the plot of thermionic-emission saturation current Ite as a function of temperature too. The proposed method of finding Φb is independent of the exact values of the metal-semiconductor contact area A and of the modified Richardson constant A∗∗. This fact can be used for determination of Φb in new Schottky structures based on multicomponent semiconductor materials.

Using the experimentally evaluated value A∗∗ = 1.796 × 106Am−2K−2 for the barrier height determination from I–V characteristics the value of Φb = 0.881 ± 0.002 eV was reached independent of temperature.

The more exact value of barrier height Φb is a relevant input parameter for Schottky diode computer-aided modeling and simulation, which provided a closer correlation between the experimental and theoretical characteristics.

Analysis of I-V measurements on PtSi-Si Schottky structures in a wide temperature range

Two methods are described to obtain the value of the series resistance (R) of a Schottky diode from its forward I-V characteristic. The value of R is then used to plot the curve ln ( I ) versus V_{D} (= V - IR) which becomes a straight line even if ln (I) versus V does not. The ideality factor n and the Schottky-barrier height \Phi_{B0} of the diode then follow from the standard procedure. The main advantages of the methods are: 1) a linear regression can be used to calculate the value of R , 2) many data points are used over the whole data range which raises the accuracy of the results, and 3) the validity of constant R assumption can be checked by the linearity of the ln (I) versus V D curve. The methods are illustrated on the experimental data of a real diode.

/pdf/an-improved-forward-i-v-method-for-nonideal-schottky-diodes-1jlagvfx6g.pdf

F.C.T. So

Papers

An improved forward I-V method for nonideal Schottky diodes with high series resistance