| Summary: | 碩士 === 國立成功大學 === 電機工程學系 === 86 === An InGaP/GaAs single heterojunction bipolar transistor (SHBT)
with an 50A setback layer and a d-doped sheet inserting between
base-emitterheterointerface was fabricated successfully and
stuided. From the theoreticalanalysis and experimental results,
it is found that the insertion of a 50Asetback layer and a d-
doped sheet can effectively eliminate the undesiredpotential-
spike at N-InGaP/GaAs heterojunction. A common-emitter current
of280 and an offset voltage as small as 55mV are obtained. In
addition, a currentgain of 11 is obtained at a very small
collector current of 0.5uA withoutthe passivation and emitter-
thinning techniques of base-emitter junction.These results
indicate that the high current gain and low offset voltage can
be obtained without the passivation of emitter-base junction. It
shows the evidencethat the potential spike is indeed reduced by
the employment of a d-doped sheet.In summary, we employ a new
method to effectively supress the potential spikewhile a high
current gain, especially at low collector current is maintained,
simultaneously. By using a d-doped sheet at the emitter-base (E-
B) heterojunction,the electron barrier, potential spike, is
reduced while the effecitive hole barrier is increased. Due to
the reduction of potential spike, the thermionic-fieldtunneling
of electrons transport across the heterojunction is decreased.
Thus,the hole confinement effect and emitter injection
efficiency may be enhanced. Furthermore,the B-E junction turn-on
voltage and the ideality factor of collector currentare reduced.
It implies that a low collector-emitter offset voltage(dVce) and
high current-gain can be obtained.
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