09 HeterostructureNotes

09 HeterostructureNotes - Heterostructures Most photonic...

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Heterostructures Most photonic devices are fabricated as heterostructures. That is the device relies on the use of materials with different energy gaps within the device structure to improve the device performance. In lasers there are several reasons to employ them to achieve high performance.Compare p-n junction to heterojunction E c E Fp E v E Fn δ n ~ e x/Ln δ p ~ e -x/Lp x x δ p, δ n 1. Carrier injection into both sides. 1. Carrier injection into small E g region. 2. Spatial extent controlled by diffusion. 2. Carriers confined in small E g region. 3. Weak light guiding mechanism. 3. Strong wave guiding of light. E c E Fp E v E Fn n 1 n 2 n 1
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To achieve the formation of HJ diodes we must be able to grow materials with the same lattice constant but different energy gaps on a common substrate and control the conductivity type. For emission at 1.55 μ m, an InP substrate is the optimal choice. There is an 0.55 eV E
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This note was uploaded on 02/23/2011 for the course EE 474 taught by Professor Lingo during the Spring '11 term at USC.

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09 HeterostructureNotes - Heterostructures Most photonic...

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