Halvleder

Der er følgende kendetegn ved et rent halvledermateriale:

• Den elektriske modstand falder med stigende temperatur. (Eks. gammeldags carbon-modstandee)
• Der er ingen frie valenselektroner i halvlederkrystalgitteret. Derfor den "dårlige" elektriske ledningsevne.

Table of contents

1 Halvlederen silicium 2 Andre halvledere 3 Kilder/referencer 4 Se også 5 Eksterne henvisninger

Halvlederen silicium

Silicium anvendes i mere end 99,9 % af halvlederkomponenterne i dag (2003).

Silicium udvindes af specielt udvalgt sand. Hovedbestanddelen i sand er SiO₂ (Siliciumdioxyd, kvarts).

Andre halvledere

• Grundstofhalvledere (hovedgruppe IV):
  • Silicium.
  • Germanium som blev brugt til dioder og transistorer fra december 1947 til i hvert fald 1980'erne. Nogle af de sidste germanium baserede transistorer hed f.eks. AF139, AF239, AF279. De blev anvendt til forstærkning i udvalgte VHF og UHF frekvensbånd i fjernsynsmodtagerens radioforsats.
  • Krystallinsk carbon (diamant i en superren form).
• Legeringshalvledere (Typisk kendetegn: Middelværdien af de 2 grundstoffers hovedgrupper giver 4):
  • Silicium og Germanium (SiGe). Halvlederkomponenter baseret på SiGe anvendes til f.eks. mobiltelefoners og WLAN-korts radiosenderdel og radiomodtagerdel. Se f.eks. NEW SiGe RF-Bipolar NPN Transistors -- BFP640 and BFP650.
  • Silicium og Carbon også kaldet Siliciumcarbid. Anvendes til højeffektive robuste SMPS strømforsyninger. Se SiC diodes.
  • Gallium og Arsen også kaldet Galliumarsenid.
  • Gallium og Nitrogen også kaldet Galliumnitrid. Anvendes i nye højeffektive solceller og blå og hvide lysdioder.
  • Indium og fosfor også kaldet Indiumfosfid. Anvendes i lysdioder som afgiver synligt lys.
  • Sort kobberoxyd (CuO) (middelværdien giver ikke 4). Se i solcelle under selvbyg.
  • Selen legeret med?. I gamle dage (1950'erne, 1960'erne) havde radiorørsbaserede radioer og fjernsyn nogle robuste dioder kaldet selen-ensrettere.
  • En halvleder baseret på: zink, mangan og tellurium. Kilde: November 10, 2003, Scientific American: Novel Semiconductor Could Soup Up Solar Cells

• http://www.firstprincipals.com/MESFET.htm Citat: "...The technology is covered by U.S. Patent 6,150,680, along with four associated foreign applications. Using a unique design approach, along with variations in processing, improvements at higher voltage and power can be achieved using III–V compounds such as GaAs, InP, and potentially GaN and SiC...."
• Infineon Technologies Produces Worlds first Power Semiconductors in Silicon Carbide Citat: "...Due to its unique characteristics, the silicon carbide (SiC) material has high blocking voltage capability (up to 3500V) resulting in a higher schottky barrier, ten times higher electrical breakdown field strength, and a thermal conductivity comparable with that of copper. ..."
• SiC Power Schottky (Barrier) Diodes (SBD) in Power Factor Correction Circuits (pdf)
• Januar 2002, Silicon carbide moves further towards commercialization Citat: "...A 3 x 4.1 mm^2 1800 V SiC JFET die was presented with a current-carrying capability of 15 A at an on-state voltage of just 2 V. ...Of the bipolar devices reported at the conference, the most impressive results came from Cree, which announced 10 kV, 200 A pulsed power performance from a 3 x 3 mm 4H-SiC pin diode. ..."
• AVTech: The Unusual Diode FAQ - IV.2 - Selenium and Copper Oxide diodes
• The Road to the Transistor, By Jed Margolin Citat: "...The copper oxide rectifier was invented in 1927 by L.O. Grondahl and P.H. Geiger...The selenium rectifier was invented in 1933 by C.E. Fitts..."

• Superleder
• Elektrisk leder
• Elektrisk isolator
• Elektricitet
• Elektrisk ledning
• Elektrisk kabel

• 4. General Aspects of Silicon (da. Silicium) Technology
• The CPU Explained: From Sand to Chip
• Emergence of a New Chip
• Posted: Sept. 27, 2000, Semiconductor Manufacturing, Peter Dunn, FACSNET High Tech Adviser
• 25 August, 2004, BBC News: Door open for silicon replacement Citat: "...Previous research has already shown that even at red-hot temperatures as high as 650C (1,202F), silicon carbide devices can function unperturbed and without the need for cooling....One exciting application for silicon carbide could be in deep-space missions, where nuclear power would be needed for the craft. Radiation-hardened silicon carbide devices would reduce the shielding needed to protect reactor control electronics..."
  • Device Research Citat: "...Silicon carbide has several unique properties that can lead to enhanced performance in devices, as discussed below...We have developed the first lateral power MOSFETs in SiC. These devices exhibit blocking voltages of 2.6 kV, a new record..."

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