EE216.W2010.Lecture6

EE216.W2010.Lecture6 - Lecture 6. P-N Junctions P-N...

Info iconThis preview shows pages 1–6. Sign up to view the full content.

View Full Document Right Arrow Icon
1 EE 216 Principles and Models of Semiconductor Devices (Winter 2010) K. C. Saraswat and R. T. Howe Lecture 6. P-N Junctions P-N junction structures and qualitative solutions in thermal equilibrium Depletion approximation and charge, field, potential, and energy bands in thermal equilibrium The Debye length: field penetration into the quasi- neutral regions Quantitative analysis of depletion width for abrupt and graded junctions in thermal equilibrium EE 216 Principles and Models of Semiconductor Devices (Winter 2010) K. C. Saraswat and R. T. Howe P-N Junction Formation P-N junctions, in addition to being a useful semiconductor device, form the basis for almost all other semiconductor devices. Understanding their operation is basic to understanding most devices Junction Fabrication by Epitaxy N(x) N P N a (x) N d (x) X P-type N-type Junction Fabrication by Ion Implantation IMPLANT N(x,t) = 2 π∆ R p Q e 2 R p 2 (x - Rp ) 2 Rp
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
2 EE 216 Principles and Models of Semiconductor Devices (Winter 2010) K. C. Saraswat and R. T. Howe DRIVE-IN N(x,t) = π Dt Q e 4Dt x 2 A variety of techniques is available to fabricate P-N junctions. The two "simple" impurity proFles that result are the erfc and Gaussian. P-N Junction Formation (Cont.) PREDEP N(x,t) = N o erfc 2 Dt x N Unlimited source Limited source EE 216 Principles and Models of Semiconductor Devices (Winter 2010) K. C. Saraswat and R. T. Howe The two proFles that are encountered most often in real devices are also easiest to analyze from a device physics point of view N(x) N P N a (x) N d (x) X ) N P x N d (x) N a (x) N(x) P-N Junction Profiles Step Junction Good approximation for shallow, high concentration junctions (x j < 1μm) and epitaxially grown junctions Linearly Graded Junction Good approximation for deep junctions (x j > 3 μm)
Background image of page 2
3 EE 216 Principles and Models of Semiconductor Devices (Winter 2010) K. C. Saraswat and R. T. Howe Thought Experiment (p, n separate) EE 216 Principles and Models of Semiconductor Devices (Winter 2010) K. C. Saraswat and R. T. Howe Thought Experiment (pn junction)
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
4 EE 216 Principles and Models of Semiconductor Devices (Winter 2010) K. C. Saraswat and R. T. Howe Band Diagrams in Thermal Equilibrium If N and P type materials are brought into contact, establishment of equilibrium takes place. Both electrons and holes move to establish equilibrium. χ = electron afFnity = E o - E c, an intrinsic property where E o = vacuum level Φ s = semiconductor work function sp = E o - E Fp = semiconductor work function of p-type Si sn = E o - E Fn = semiconductor work function of n-type Si EE 216 Principles and Models of Semiconductor Devices (Winter 2010) K. C. Saraswat and R. T. Howe Band Diagrams at Equilibrium
Background image of page 4
5 EE 216 Principles and Models of Semiconductor Devices (Winter 2010) K. C. Saraswat and R. T. Howe
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 6
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 06/05/2010 for the course EE 216 taught by Professor Harris,j during the Fall '09 term at Stanford.

Page1 / 14

EE216.W2010.Lecture6 - Lecture 6. P-N Junctions P-N...

This preview shows document pages 1 - 6. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online