本征半导体和非本征半导体

半导体物质具有位于绝缘体和导体之间的电特性。 Si和Ge是半导体的最大例子。有两种类型的半导体：本征半导体和非本征半导体（p型和n型）。本征型半导体是纯的，但泛型型半导体含有杂质，使其具有导电性。在环境温度下，本征电导率为零，但外在电导率最小。通过掺杂和能带图，本文提供了本征和外征半导体的概述。

本征半导体

The definition of an intrinsic semiconductor is a semiconductor that is exceedingly pure. According to the energy band theory, the conductivity of this semiconductor will be zero at ambient temperature. Si and Ge are two examples of intrinsic semiconductors.

• 在下面的能带图中，导带是空的，但价带是完全填满的。一旦温度升高，就可以为其提供一些热能。作为退出价带的结果，来自价带的电子被提供给导带。

• 当电子从价带移动到导带时，电子的流动将是随机的。晶体的孔也可以在任何方向自由流动。
• 结果，该半导体的 TCR 将为负值（电阻温度系数）。 TCR 表明当温度升高时，材料的电阻降低，其电导率升高。

外在半导体

Extrinsic semiconductors are semiconductors that have had an impurity introduced to them at a regulated rate to make them conductive.

• 虽然可以掺杂绝缘材料以制成半导体，但也可以掺杂本征半导体以制成非本征半导体。
• 由于掺杂，非本征半导体分为两类：具有额外电子的原子（n 型表示负电子，来自 V 族）和具有较少电子的原子（p 型表示正电子，来自 III 族）。
• 掺杂是有目的地将杂质引入非常纯或本征的半导体中，以改变其电特性。半导体的种类决定了杂质。非本征半导体是轻到中度掺杂的半导体。

What is Doping?

Doping is the process of introducing an impurity into a semiconductor. During the production of extrinsic semiconductors, the amount and kind of impurity to be introduced to the material must be carefully monitored. In most cases, one impurity atom is introduced to every 10⁸ semiconductor atoms.

Impurity is used to enhance the number of free electrons or holes in a semiconductor crystal, making it more conductive. A significant number of free electrons will exist if a pentavalent impurity with five valence electrons is introduced to a pure semiconductor. A significant number of holes will exist in the semiconductor if a trivalent impurity with three valence electrons is introduced. Extrinsic semiconductors are divided into two categories based on the type of impurity added: N-type and P-type semiconductors.

n 型半导体

N-type semiconductors are extrinsic semiconductors in which dopant atoms can provide additional conduction electrons to the host material (e.g. phosphorus in silicon).

结果导致过多的负（n型）电子电荷载流子。掺杂原子通常比主体原子包含一个额外的价电子。 V族元素在IV族固体中的原子置换是最典型的情况。当宿主包含多种类型的原子时，问题变得更加复杂。例如，硅在取代镓时可以充当供体，或者在取代砷化镓等 III-V 半导体中的砷时充当受体。一些供体的价电子比主体少，例如碱金属，它们是大多数固体中的供体。

p型半导体

To enhance the number of free charge carriers, a p-type (p for “positive”) semiconductor is formed by adding a certain type of atom to the semiconductor.

当掺杂物质被引入时，它会从半导体原子中去除（接受）弱键合的外层电子。电子留下的空位称为空穴，这种掺杂剂也称为受体物质。 p型掺杂的目标是产生大量的空穴。

在硅的例子中，晶格被三价原子交换。结果，通常构成硅晶格的四个共价键之一缺少电子。结果，掺杂原子可以接受来自附近原子的共价键的电子以完成第四键。因此，受主是这些掺杂剂的名称。

当掺杂原子吸收一个电子时，它会导致附近的原子失去一半的链接，从而产生一个空穴。每个空穴都连接到相邻的带负电的掺杂剂离子，从而形成电中性半导体。一旦每个空穴都偏离了晶格，空穴位置处的原子中的一个质子将被“暴露”，这意味着它将不再被电子抵消。这个原子将在其核中包含三个电子和一个空穴，其中将有四个质子。

结果，一个空穴的行为就像一个正电荷。当提供足够多的受体原子时，热激发电子的数量大大超过空穴。在 p 型材料中，空穴是多数载流子，而电子是少数载流子。

内在和外在半导体之间的区别

以下是非本征和本征半导体之间的一些主要区别：

• 本征半导体始终以其最纯净的形式存在，而本征半导体是通过在纯半导体中掺杂杂质而产生的。
• 在室温下，与其他材料相比，本征半导体的导电性较差，而非本征半导体的导电性较高。
• 电子数等于本征半导体中的空穴数，而本征半导体中的电子数不相等。
• 本征半导体仅依赖于温度，而外征半导体则受温度和存在的污染物数量的影响。
• 本征半导体没有进一步分类，而N型和p型半导体是非本征半导体中的两种半导体。
• 硅和锗是本征半导体的两个示例，而掺杂有 Al、In、P、As 和其他元素的 Si 和 Ge 是本征半导体的示例。

示例问题

问题一：什么是n型半导体？

回答：

When a tetravalent element such as Silicon or Germanium is doped with a pentavalent element such as Arsenic (As) or Antimony, the result is an n-type semiconductor (Sb). Thus in the crystal lattice, one atom of the pentavalent element takes the place of an atom of the four valent elements.

All five pentavalent atom electrons establish strong connections with their tetravalent neighbours, and the fifth electron creates a weak bond with its parent element after the doping process is complete. A relatively little amount of energy is needed to ionise the fifth electron. Although it is in the tetravalent element’s crystal structure, the fifth electron is also free to roam about even at room temperature.

问题2：什么是P型半导体？

回答：

When a tetravalent element such as silicon or germanium is doped with a three-valent element such as aluminium (Al), indium (In), etc., the result is a P-type semiconductor. After doping, three of the tetravalent element’s four electrons establish a covalent connection with the trivalent element’s three electrons. There is a deficit of one electron, and as a result, the fourth electron has no electron with which to bind.

As a result, a void or hole is produced, and it becomes necessary to fill it. As a result, an electron in the outer orbit of a nearby atom has a chance to leap and fill the void. In this way, one electron is removed from the system, leaving a void or a hole in its stead. Conduction can then occur through the hole.

问题3：在锗金属中掺杂少量铟会有什么结果？

回答：

P-type semiconductors are made from germanium impurities that include indium. Impurities of a trivalent nature can be added to germanium to generate the P-type material. They are called acceptor impurities because they are trivalent.

问题4：由于晶体键的断裂而在其中流动电流的纯半导体晶体的名称是什么？

回答：

Intrinsically pure semiconductors are referred to be that. The conduction band has an identical amount of electrons as it has holes and vice versa. In addition to being termed intrinsic semiconductors, undoped semiconductors and i-type semiconductors are other names for intrinsic semiconductors.

问题5：在以下哪种情况下，孔占电流的大部分？

回答：

The bulk of charge carriers in p-type extrinsic semiconductors are holes, which are amorphous semiconductors. They are called acceptor impurities because they are trivalent. The minority charge carriers in p-type semiconductors are electrons.