Experiment#1: Diode Characteristics. Aims of the experiment: To measure the current-voltage characteristics of a silicon and a germanium diodes. Theory: A semiconductor is a material that is between conductors and insulators in its ability to conduct electrical current, such as silicon and germanium. Charge carriers in a semiconductor can be negative, positive, or both. When an electron moves from the valence band into the conduction band, it leaves behind a vacant site, called a hole. The process of adding impurities to a semiconductor, called doping, is important in controlling the conductivity of semiconductors. The impurity atom that gives a free electron is called a donor atom. Semiconductors doped with donor atoms are called n-type semiconductors because the majority of charge carriers are electrons, which are negatively charged. The impurity atom that accepts an electron is called an acceptor atom. Semiconductors doped with acceptor atoms are known as p-type semiconductors because the majority of charge carriers are positively charged holes. A diode is a device that is based on a single pn junction, where a semiconductor crystal is doped with p-type one side and with n-type on the other side. The region between these two sides is devoid of any charge carriers, due the diffusion of n-side electrons nearest the junction to the p side holes: this region is called the depletion region. The systematic symbol of diode is shown beside. The arrow in the symbol points in the direction of holes current (opposite to electron flow).The role of a diode is to PN Junction pass current in forward direction but not the reverse direction. and Diode symbol This way diode acts like a valve. In forward biasing, a voltage is applied to a diode such that the p side is connected to the positive terminal of a voltage source, so the charge carriers are derived into the depletion region, allowing current to flow through the diode. The forward voltage Forward Bias. Fahad Bin Sultan University Electronics Lab. Experiment#1: Diode Characteristics. Aims of the experiment: To measure the current-voltage characteristics of a silicon and a germanium diodes. Theory: A semiconductor is a material that is between conductors and insulators in its ability to conduct electrical current, such as silicon and germanium. Charge carriers in a semiconductor can be negative, positive, or both. When an electron moves from the valence band into the conduction band, it leaves behind a vacant site, called a hole. The process of adding impurities to a semiconductor, called doping, is important in controlling the conductivity of semiconductors. The impurity atom that gives a free electron is called a donor atom. Semiconductors doped with donor atoms are called n-type semiconductors because the majority of charge carriers are electrons, which are negatively charged. The impurity atom that accepts an electron is called an acceptor atom. Semiconductors doped with acceptor atoms are known as p-type semiconductors because the majority of charge carriers are positively charged holes. A diode is a device that is based on a single pn junction, where a semiconductor crystal is doped with p-type one side and with n-type on the other side. The region between these two sides is devoid of any charge carriers, due the diffusion of n-side electrons nearest the junction to the p side holes: this region is called the depletion region. The systematic symbol of diode is shown beside. The arrow in the symbol points in the direction of holes current (opposite to electron flow).The role of a diode is to PN Junction pass current in forward direction but not the reverse direction. and Diode symbol This way diode acts like a valve. In forward biasing, a voltage is applied to a diode such that the p side is connected to the positive terminal of a voltage source, so the charge carriers are derived into the depletion region, allowing current to flow through the diode. The forward voltage Forward Bias. Fahad Bin Sultan University Electronics Lab