| Long wavelength In0.53Ga0.47As photodiodes as well as In0.52Al0.48As/In0.53Ga0.47 As high electron mobility transistors (HEMTs) have mainly been fabricated on InP based material systems because these ternary materials are lattice matched to InP substrates. However, the several practical shortcomings of InP substrates such as mechanical fragility, high substrate cost, and small wafer size motivated the development of metamorphic devices on GaAs substrates. In this dissertation, high speed metamorphic double heterojunction photodiodes were designed and fabricated on metamorphic GaAs substrates for long-wavelength optical fiber communication applications. The use of a novel double heterostructure employing an InGaAlAs optical impedance matching layer, a chirped InGaAs/InAlAs superlattice graded bandgap layer (SL-GBL), and a large bandgap I-InAlAs drift region enabled photodiodes to achieve a low dark current of 500 pA, a responsivity of 0.6 A/W, and a −3 dB bandwidth of 38 GHz at −5 V reverse bias for 1.55 μm light. The photodiode heterostructure optimized for higher bandwidth by scaling the thickness of undoped In0.53Ga0.47 As and In0.52Al0.48As layers has demonstrated over 60 GHz bandwidth at 1.55 μm wavelength. Long wavelength In0.53 Ga0.47As photodetectors and In0.52Al0.48 As/In0.53Ga0.47As high electron mobility transistors (HEMTs) were monolithically integrated on metamorphic GaAs substrates for optoelectronic receiver application. By stacking the photodiode layers on top of HEMT layers, the performance of both devices can be optimized separately. The measured performance of both devices opened the possibility of ultra-high speed monolithic optoelectronic receiver circuits operating at 1.55 μm on metamorphic GaAs substrates. |
