_{1}

^{*}

It is shown that the mean value of the capacitive current arising in the p-n-junction in a microwave field is zero, and the average value of the active current independently of the current value is different from zero and is equal to the current generated by the diode.

Under the influence of the electromagnetic wave the average energy of the charge carriers increases in the p-n-junction. As a result, through the potential barrier, current of hot electrons and holes flows. On the other hand, due to changing of the height of the barrier at the contact, alternating current generated by the electric field of the wave will be rectified. Due to the fact that the directions of the currents of hot carriers and rectified currents are the same, so defining the true mechanism of generation of electromotive force (EMF) on diode is an important issue. The interaction of an electromagnetic field with a semiconductor heats the free electrons and holes, and the electrons directly interact with phonons, which lead to heating of the semiconductor [

In [

Effect of warming up of the charge carriers in the operation of semiconductor rectifying structures was first considered by G. M. Avakyantsom [

In the p-n-junction with the hot carriers thermoelectric power for the different currents was studied and CVC was theoretically obtained in thin p-n-junction. In the paper of Guliamov G. and Shamirzaev S. H. [

The aim of this work is to study and compare the active and capacitive conductivity arising in the p-n-junc- tion in a strong microwave field.

To calculate the EMF and currents generated in the p-n junction the differential conductance in the form of active and reactive components I_{a} and I_{r} can be written in the following form [

Here,

here, e is the charge of an electron, T is the lattice temperature, k is the Boltzmann constant, p_{n}―concentration and L_{p}―diffusion length of holes into the n region, t_{p} and m_{p}―respectively the lifetime and mobility of holes, U_{0}―applied voltage, w―cyclic frequency.

Consider the ratio of the second term to the first in Equation (1):

We estimate Equation (4) in the microwave range. For this we use the typical parameters of the samples used in the experiments A. I. Veyngera and others [^{10} Hz, t_{p} = 10^{−5} s. Then the ratio of the first term to the second, we have ~3 × 10^{5}. This shows that the reactive current by several orders of magnitude higher active current conduction.

Based on these facts we can conclude that in the experiments capacitance diode completely bypasses its active differential resistance R_{g}. Indeed, at frequencies of the order of ν = 10^{10} Hz capacitive diode current will be much larger than the active current through the p-n junction. In this case, the active conductivity of the p-n-junc- tion is heavily shunted by the capacitive conduction of the diode and the sample is almost completely loses its rectifying property. In experimental studies [

On the other hand the total current density is made up of convection currents and displacement currents:

Here, the first term is an active, and a second capacitive current, I_{с}(t)―current density of convection associated with the motion of free charges,

We estimate the current convection and the bias current in the p-n-junction, located in a microwave field. Convection current can be written as:

Here U(t)―can be estimated by the formula [

where P―Power,

the p-n-junction

total current through the diode can be written as follows:

Here

Leaving the diode current when exposed to microwave field is determined by the average current during the period of the wave. We average the total current in the microwave field:

We calculate the average value of the bias current:

The electric field is a periodic function of time

This current is due to the active current, a capacitive current will not affect the average value of the total current emitted from the diode. This is a simple but important conclusion to explain averaged currents arising on different diodes when exposed to the electromagnetic field. It should be noted that the expression of BAX p-n-junction (11) corresponds to any diode with an asymmetric p-n-junction. For example, contact metal-semi- conductor, Schottky diode, a tunnel diode, metal-insulator-metal and others can relate to these diodes.

Based on the analysis of the results obtained it can be concluded that no matter how large the capacitive current is, its average value is zero. Because the electric field is a periodic function of time with period T. No matter how small the active current is, the average value is not zero, and the average current generated by diode is determined precisely by this current. In p-n junction, the active current is closed with the recombination current and total average current is determined by recombination of electrons and holes.

The author would like to thank G. Gulyamov, G. Dadamirzayev and N. Yu. Sharibayev for numerous discussions.

Muhammadjon GulomkodirovichDadamirzaev, (2015) Active and Capacitive Conductance of the Diode in a Strong Microwave Field. Journal of Applied Mathematics and Physics,03,1684-1687. doi: 10.4236/jamp.2015.312194