Lecture

Induced Photodiodes: Principles and Applications

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Description

This lecture discusses the principles and applications of induced photodiodes, particularly focusing on the induced PN junction with black silicon. The instructor explains the structure of the photodiode, which consists of a low-doped N-silicon substrate and P layers at the surface, coated with aluminum oxide. The lecture highlights the advantages of using black silicon, emphasizing its ability to achieve total light absorption across various wavelengths due to its nanostructured surface. The instructor details the working mechanism, describing how light absorption generates electron-hole pairs, with electrons moving to the substrate and holes collected in the P-channel. The concept of an induced PIN photodiode is introduced, along with comparisons to ion-sensitive field-effect transistors (ISVETs). The lecture also covers the impact of pH levels on the performance of ISVETs, illustrating how the threshold voltage varies with the presence of positive or negative ions. Overall, the lecture provides a comprehensive overview of the induced photodiode's functionality and its potential applications in optical detection.

Official source

Ontological neighbourhood

Physics

Condensed matter physics: Solid-state physics

Related concepts (32)

Field-effect transistor

The field-effect transistor (FET) is a type of transistor that uses an electric field to control the flow of current in a semiconductor. FETs (JFETs or MOSFETs) are devices with three terminals: source, gate, and drain. FETs control the flow of current by the application of a voltage to the gate, which in turn alters the conductivity between the drain and source. FETs are also known as unipolar transistors since they involve single-carrier-type operation.

Depletion region

In semiconductor physics, the depletion region, also called depletion layer, depletion zone, junction region, space charge region or space charge layer, is an insulating region within a conductive, doped semiconductor material where the mobile charge carriers have been diffused away, or have been forced away by an electric field. The only elements left in the depletion region are ionized donor or acceptor impurities. This region of uncovered positive and negative ions is called the depletion region due to the depletion of carriers in this region, leaving none to carry a current.

Depletion and enhancement modes

In field-effect transistors (FETs), depletion mode and enhancement mode are two major transistor types, corresponding to whether the transistor is in an on state or an off state at zero gate–source voltage. Enhancement-mode MOSFETs (metal–oxide–semiconductor FETs) are the common switching elements in most integrated circuits. These devices are off at zero gate–source voltage. NMOS can be turned on by pulling the gate voltage higher than the source voltage, PMOS can be turned on by pulling the gate voltage lower than the source voltage.

Threshold voltage

The threshold voltage, commonly abbreviated as Vth or VGS(th), of a field-effect transistor (FET) is the minimum gate-to-source voltage (VGS) that is needed to create a conducting path between the source and drain terminals. It is an important scaling factor to maintain power efficiency. When referring to a junction field-effect transistor (JFET), the threshold voltage is often called pinch-off voltage instead.

P–n junction

A p–n junction is a boundary or interface between two types of semiconductor materials, p-type and n-type, inside a single crystal of semiconductor. The "p" (positive) side contains an excess of holes, while the "n" (negative) side contains an excess of electrons in the outer shells of the electrically neutral atoms there. This allows electric current to pass through the junction only in one direction.

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