Understanding the Atomic Structure of Semiconductors and the Semiconductor Bottleneck Problem

Nov 22 - 2023

conductivityFor example, we all know that metal copper is a conductor. Observing its atomic structure diagram, we will find that its outermost layer only has one electron. We call this electron a valence electron because the attraction between the atomic nucleus and valence electrons is relatively small. Therefore, once attracted by external forces, this electron is easily detached from the copper atom and becomes a free electron, which is also the main reason why copper can become a conductor. Similarly, by observing the atomic structure of insulators,semiconductor testing it can be observed that they typically have eight additional electrons and are extremely stable. As the name suggests, semiconductors should be somewhere between the two.

So what is its atomic structure like?

Observing the periodic table of elements reveals that the elements near the boundary between conductors and insulators are important materials for making semiconductors. Of course, silicon is the most influential element. Observing the atomic structure diagram reveals that it has four electrons on its outermost layer. To achieve an equilibrium state, one is either abandoning four electrons or pulling in four electrons, while silicon atoms cleverly share the top, bottom, left, and right electrons when arranged, forming a stable eight electron structure, known as covalent bonds, hand in hand.

So where does the conductivity of silicon come from?

When the temperature is greater than absolute zero, electrons in the frame band may undergo a transition and become free electrons. At the same time, a hole will be formed at the original position, which means that there will be an equal amount of free electrons and holes in the silicon crystal, which can play a conductive role. This is a pure semiconductor, also known as an intrinsic semiconductor. Although its structure is perfect,semiconductor failure analysis to increase the conductivity of semiconductors, other elements need to be doped. When we replace silicon atoms with pentavalent phosphorus atoms, we can increase the concentration of free electrons and obtain N-type semiconductors. Similarly, if silicon atoms are replaced with boron atoms with only three electrons in the outermost layer, and the concentration of space is increased, a trapezoidal semiconductor can be obtained.

So what happens when these two types of semiconductors are connected together? The electrons in the N region urgently want to diffuse to the P region, and the holes in the P region desperately want to diffuse to the N region. At this point, an internal electric field from N to P will form, preventing diffusion from proceeding. After the two reach dynamic equilibrium, a space charge region will be formed at the interface, which is the PN section. The PN section has a single conductivity, and our common diodes are made using this characteristic. By using sunlight to irradiate PN nodes, electron holes are excited to separate the charges passing through the interface layer, forming a photo generated electric field directed from P to N. This is the photogenerated volt effect, which is also the fundamental principle of solar cells.

What is the semiconductor bottleneck problem?

A chip, in simple terms, is an integrated circuit made of semiconductor materials.

Chips are the most important components in the information industry, such as mobile phones, computers, automobiles, high-speed railways, power grids, etc. These fields all require a large number of chips. It can be said that wherever information is involved, chips are needed. However, commonly used computer core chips, high-end mobile phone core chips, display driver chips in video systems, digital signal processing device chips,aotomatic prober and programmable logic device core chips are all high-end chips that we currently cannot produce, almost entirely relying on imports. Due to our high dependence on the external market and the technical barriers that are difficult to break through in the short term, we are particularly passive when we are stuck in the neck.

We know that domestic chips often suffer from "bottleneck" technology in the United States, which mainly involves three aspects: first, the manufacturing process; The second is equipment/materials; The third is to design IP cores/EDA tools.

However, in the long run, the development of China's semiconductor industry has advantages such as industrial cluster advantages, cost advantages, and market size. Driven by import substitution and industrial upgrading, the prospects of China's semiconductor industry are bright.