SEMICONDUCTOR DEVICE PHYSICS AND DESIGN

6.1. INTRODUCTION 247

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0 0.5 1 1.5 2 2.5^0

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J (mA/mme

2 )

Vce (V)

Ajbe= 0.6 x 4.3 μm^2

Ib step = 85 uA

Vcb = 0 V

Peak fτ, fmax cI (mA)

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Gains (dB)

Frequency (Hz)

ft = 391 GHz, fmax = 505 GHz

U

H 21

Ajbe = 0.6 x 4.3 um^2

Ic = 13.2 mA, Vce = 1.54 V

Je = 5.17 mA/um^2 , Vcb= 0.6 V

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123456

GHz

Je (mA/um^2 )

ft

fmax

Vcb = 0.6 V

(a)

(b)

(c)

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C

Figure 6.1: State of the artn-InP/p+-InGaAs/n−-InP double heterojunction bipolar transistor
(DHBT). (a)SEM image of device, (b) dc I-V characteristics, and (c) high frequency current
gain and power gain. For this device, the averageβ≈ 36 andVBR,CEO=5. 1 V (measured at
IC=50μA). Figures courtesy of M. Rodwell and Z. Griffith, UCSB.

the faucet example, these two requirements mean we should be able to turn the faucet on and off
with little effort and the water should not leak out of the faucet head!
In this chapter we will discuss static characteristics of the bipolar transistor.