# To draw the IV characteristic curve for p n junction in forward and reverse bias

Forward bias and reverse bias is always present within a standard diode, especially while drawing the characteristics of I-V junction and P-N junction. The curve of these junctions is dependent on the forward and reverse bias and follows a series of steps and procedures to successfully draw the curve within a standard diode.

## Definition of Forward and Reverse Bias

Forward bias is the state where the external voltage is always delivered across the P-N junction within a standard diode. In the set-up process of the forward bias, the P side of the standard diode is always attached to the positive terminal. The N side on the other hand, is fixed to the negative side of a battery that is powering the standard diode in the first place (Circuitglobe, 2022).

Figure 1: Forward bias

In a forward bias the barrier potential is always reducing and the voltage present within this bias consists of an anode that is greater than the cathode. The depletion layer is thin and the forward current is large within a forward bias (Razera et al. 2020). In addition, this type of bias has a low resistance along with the dependence on the forward voltage in real-time.

Reverse bias on the other hand, is a present when the P-side of a standard diode is connected directly to the negative voltage of a battery in real-time. Here, the N-side connects with the positive voltage of the battery that eventually creates the depilation layer within a standard diode.

Figure 2: Reverse bias

The reverse bias has a thick depletion layer that makes it very high on resistance. It eventually prevents the flow of current within a standard diode that has zero magnitude of current while flowing through the circuits (Circuitglobe, 2022). The reverse bias also operates as an insulator where the forward current flows with a small flow with a strengthened barrier flow.

## Required apparatus

The process of drawing the characteristics of I-V and P-N junction involves a series of apparatus that are needed to complete the process in real-time. Here, the first required material is a P-n junction diode along with two batteries with the powers of 3-volt and 50-volt. After that, a high resistance rheostat is required with two voltmeters and two ammeters. The powers of the voltmeters should be 0-3 volts and 0-50 volts and for the ammeter, the values need to be 0-100 mA and 0-100 μA. Apart from these materials, a one-way key, come connecting wires and a piece of sandpaper is required for this process.

## Procedures followed

In this procedure, first, the circuit connections should be neat, clean and tight and all the possible errors should be checked. After that, the voltmeter and milli-ammeter rheostat needs to be closer to the K key. Then the biases need to be applied by keeping current to the power of zero. In order to increase the biases, the power needs to be upgraded to 0.3, 0.4 and 0.7 respectively (Etechnog, 2022). After that, all the keys should be taken out and the VF should be forwarded to the breakdown stage. Finally, the observations during these processes need to be documented for further assistance.

## Applied theories

In the P-N junction of a standard cathode, the forward bias is placed in the frontline when the p-section is connected to the positive terminal and the n-section is connected to the negative terminal of a battery (Pribyl-Kranewitter et al. 2021). According to the theory, when the voltage within the battery increases, the current also increases suddenly.

Figure 3: I-V Characteristics Graph

In the case of the reverse bias characteristics, the junction P-section is connected to the negative terminal and the N-section is connected to the positive terminal of a battery (Coolgyan, 2022). So, when the voltage increases within a battery, a small change can be spotted within the battery and it eventually increases the voltage to a higher value.

## Observations

Sl. no. Forward bias voltage VF in V Forward current IF in mA

Table 1: Observation from the forward bias in the I-V and P-N junction

Sl. no. Reverse bias voltage VR in V Reverse current IR in μA

Table 2: Observation from the reverse bias in the I-V and P-N junction

## Conclusion

Forward and reverse bias are involved integrally with the drawing of the characteristics of I-V junction and P-N junction. In the case of forward bias, the applied voltage is always opposite to the potential barrier junction. An ample range of materials is required to start the drawing process along with the theories of forward bias and reverse bias in real-time.

## FAQs

Q1. What are some of the precautions involved in drawing the I-V and P-N junction of forwarding and reverse bias?

In the drawing process of the I-V and P-N junction, the connections should always be neat and clean along with proper and supportive keys. Additionally, in the breakdown process the forward and the reverse bias should not be applied directly.

Q2. What is the main source of error within the forward and reverse bias?

The primary source of error within the forward and reverse bias involves a faulty junction within the diode. This appears as the main source of error when drawing the I-V and P-N junction in the forward and reverse biases.

Q3. What are some of the energy bands used in the forward and reverse bias within a standard diode?

The forward and reverse bias can use the conduction band (C) and the valence band (V) within a standard diode. Under different circumstances, it can also use the forbidden band (F) of the forward and reverse biases within a standard diode in real-time.

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