You are given a PN junction where the with doping of NA=1017cm-3 and ND=2x1015cm-3. The band diagram of the PN junction at thermal equilibrium is given in the figure below.给你一个 PN 结，其中掺杂的 NA = 1017cm-3，ND = 2x1015cm-3。热平衡处 PN 结的能带图载于下图。

What is the carrier concentration at point "A" above the energy level ECn? (use scientific notation, e.g. 1e17 for 1017).高于能级 ECn 的 “a” 点的载流子浓度是多少？ (使用科学记数法，例如 1e17 表示 1017)。

[Fill in the blank],
cm厘米-3

What is the carrier concentration at point "A" above the energy level ECp?在能级 ECp 以上的 “a” 点的载流子浓度是多少？

[Fill in the blank],
cm厘米-3

Question

You are given a PN junction where the with doping of NA=1017cm-3 and ND=2x1015cm-3. The band diagram of the PN junction at thermal equilibrium is given in the figure below.给你一个 PN 结，其中掺杂的 NA = 1017cm-3，ND = 2x1015cm-3。热平衡处 PN 结的能带图载于下图。

What is the carrier concentration at point "A" above the energy level ECn? (use scientific notation, e.g. 1e17 for 1017).高于能级 ECn 的 “a” 点的载流子浓度是多少？ (使用科学记数法，例如 1e17 表示 1017)。

[Fill in the blank],
 cm厘米-3

What is the carrier concentration at point "A" above the energy level ECp?在能级 ECp 以上的 “a” 点的载流子浓度是多少？

[Fill in the blank],
 cm厘米-3

BlackTom AI · Accepted Answer

We are given a PN junction with NA = 1e17 cm^-3 and ND = 2e15 cm^-3 and asked to find carrier concentrations at two specified energy points relative to ECn and ECp, respectively.

First, recall the standard relationships in doped semiconductors at thermal equilibrium:
- In the n-type region (donor-doped side), the majority carrier electrons concentration n is approximately equal to the donor concentration ND (n ≈ ND) when the doping is not compensated and the intrinsic concentration ni is small in comparison.
- In the p-type region, the minority carrier electron concentration is given by n ≈ ni^2 / NA, since holes dominate and electron concentration is set by intrinsic generation-recombination with the acceptor density NA.
- The intrinsic concentration ni is a small, temperature-dependent constant for silicon at room temperature, with ni^2 on the order of 10^20 cm^-6, so ni^2/NA yields a modest electron concentration on the p-side.

Now, address each blank in turn.

1) Carrier concentration at point A above the energy level ECn (in the n-region, above ECn):
- Above the conduction-band edge ECn in the n-type region, the electron concentration is governed by the donor-doped n-type semiconductor behavior. Since ND = 2e15 cm^-3, and the depletion region does not drastically alter bulk n in the heavily doped region for this order-of-magnitude assessment, n ≈ ND.
- Thus, the carrier concentration is approximately 2e15 cm^-3. This matches the expected scale for electrons in the ND-doped region, where donors supply the majority carriers.

2) Carrier concentration at point A above the energy level ECp (in the p-region, above ECp):
- In the p-type region, the majority carriers are holes, and the electron concentration (the minority carrier concentration) is given by n ≈ ni^2 / NA. With NA = 1e17 cm^-3 and room-temperature ni ≈ 1e10 cm^-3, ni^2 ≈ 1e20 cm^-6.
- Therefore, n ≈ (1e20) / (1e17) = 1e3 cm^-3. If we take a more precise ni value (approximately 1.5e10 cm^-3 for silicon at 300 K), ni^2 ≈ 2.25e20, which yields n ≈ 2.25e3 cm^-3.
- The provided numerical result 2.25e3 cm^-3 corresponds to using ni ≈ 1.5e10 cm^-3, which is a common room-temperature value for silicon. This aligns with the expectation that the electron concentration just above the valence-band-related level on the p-side is a small minority-carrier concentration determined by ni^2/NA.

Summary of the two blanks:
- Above ECn: n ≈ 2e15 cm^-3, reflecting the ND-dominated electron concentration in the n-region.
- Above ECp: n ≈ 2.25e3 cm^-3, reflecting the minority-carrier electron concentration in the p-region given by ni^2/NA using a typical ni value.

If you encounter alternative numbers, they would typically differ by using a different ni value or by misapplying the ND/NA relationships for minority vs. majority carriers. The key concept is that the n-concentration on the n-side is set by donor density, while on the p-side the minority electron concentration is controlled by ni^2/NA.

类似问题

How would the forward current and reverse current of a P+/N junction change when the temperature increases?

Which of the following PN junction has the most asymmetric current with respect to forward and reverse bias?

How did Egyptian culture and governance change during the Ptolemaic period compared to the pharaonic period?

Name the Supreme Court decision that removed financial constraints on PACs.

Political scientists Joshua Kalla and David Broockman find that senior policy makers made themselves available to _____ between three and four times more often than they did to constituents.

Name the political scientist who argues that parties are designed to serve the needs of ambitious politicians (namely candidates and officeholders).

Name the political scientist who said this famous quote about the problems of pluralism: “The flaw in the pluralist heaven is that the heavenly choir sings with a strong upper-class accent.”

更多留学生实用工具

智能学习助手

风格化写作助手

论文查重助手

文献引用助手

课堂转译助手

课堂笔记助手

Quiz搜索助手

学校历年真题

智能刷题助手

智能匹配练习

希望你的学习变得更简单