Thermal properties of metamorphic buffer materials for growth of inp double heterojunction bipolar transistors on gaas substrates

Abstract

Metamorphic double heterojunction bipolar transistors (MDHBT) using InP or InAlP as metamorphic buffer layers were grown on GaAs substrates. For devices using InP buffer layers on GaAs substrates, measured junction-ambient temperature rise at 7.5 mW power dissipation is comparable to those of devices grown on InP substrates, while much larger temperature rises are observed when InAlP buffer layers are employed. By comparing the measured temperature rise with that computed as a function of the known transistor geometry and unknown buffer-layer thermal conductivity, we estimate that the thermal conductivity of a uniform InP buffer layer is 35 5 W/k-m, while a linearly graded InAlP buffer layer with 0.2 m InP upper layer has 8 3 W/k-m effective thermal conductivity. These results strongly suggest the use of InP metamorphic buffer layers in metamorphic InP-based DHBTs grown on GaAs substrates.

Development of 6.00Å graded metamorphic buffer layers and high performance In0.86Al0.14As∕In0.86Ga0.14As heterojunction bipolar transistor devices

“…8,9 Linear composition grade was employed with no overshoot to achieve a 6.00 Å lattice parameter on InP. 15 Performance of 6.00 Å HBT devices is expected to improve with the development of thin ͑Ͻ1 m͒ metamorphic buffer layers. [10][11][12][13] In this study, 6.00 Å HBTs with lattice-matched In 0.86 Al 0.14 As and In 0.86 Ga 0.14 As emitter and base layers, respectively, were explored to mitigate the epilayer design challenges associated with device performance.…”

“…Similar approaches have been investigated over the years involving growth of graded metamorphic buffer layers on GaAs substrates. Even though ternary buffer layers are expected to have greater thermal resistance than binary layers, 14,15 this parameter could be lowered by the thickness reduction of the 6.00 Å GBLs. Narrow band gap material groups containing lattice-matched 6.00 Å In 0.86 Al 0.14 As/ In 0.86 Ga 0.14 As offer multiple advantages due to their low turn-on voltage with an energy band gap in the In 0.86 Ga 0.14 As base of 0.45 eV and low base-collector bias ͑V cb Ͻ 0.5 V͒ voltages compared to conventional lattice-matched InP HBTs, resulting in 50% reduction in power consumption.…”

InGaAs–InP Metamorphic DHBTs Grown on GaAs With Lattice-Matched Device Performance and<tex>$f_tau$</tex>,<tex>$f_max≫268$</tex>GHz

“…For these devices to be useful in high speed circuit applications, a low ratio (high ) is necessary [4]-this requires the device operating temperature be addressed during device design [5]. Because the metamorphic buffer layer can have a significant impact on the thermal resistance of the HBT, InP is used for its higher thermal conductivity [6]. Here, we report InP-based metamorphic DHBTs (mHBT) with a 268 GHz and 339 GHz , and low collector leakage current of 90 pA at V [7].…”