Delong Cui

Enhanced transmission line model structures for accurate resistance evaluation of small-size contacts and for more reliable fabrication

Two new transmission line model (TLM) techniques are presented, The first structure, LT-TLM, provides very accurate determination of the transfer length LT (within 5%) and the contact resistivity /spl rho//sub C/ (within 12%) of lateral contacts, as compared to typical errors of 30% and 50%, respectively, for conventional TLM patterns, accurate determination of these quantities is important for the optimal design of small lateral contacts in high-performance devices, such as heterojunction bipolar transistors (HBTs). The second structure, a modified concentric TLM pattern, provides the same results as conventional TLM patterns; however, they do not require mesa isolation, and they can be fabricated extremely reliably. In contrast, conventional concentric TLM patterns are often shorted together or distorted by lift-off metallization processes. Both theoretical analysis and experimental verification with analysis of the accuracy of the extracted data is presented for each technique, demonstrating the advantages of these approaches.

Impact of doping and MOCVD conditions on minority carrier lifetime of zinc- and carbon-doped InGaAs and its applications to zinc- and carbon-doped InP/InGaAs heterostructure bipolar transistors

The impact of doping and metalorganic chemical vapour deposition growth conditions on the minority carrier lifetime of zinc- and carbon-doped InGaAs is reported. Room temperature photoluminescence measurements have been employed to obtain direct information on the non-radiative lifetime of the materials. Low growth temperature and low V/III ratio lead to the lower carrier lifetime of the carbon-doped InGaAs samples. InP/InGaAs heterostructure bipolar transistors were grown and fabricated using both zinc- and carbon-doped InGaAs layers as the base regions. The current gain values measured for these devices agree well with the values calculated from the carrier lifetime and mobility/diffusion coefficient measurements.

Minority carrier lifetime in MOCVD-grown C- and Zn-doped InGaAs

Heavily C-doped p-type InGaAs has been successfully grown by metalorganic chemical vapor deposition using CBr/sub 4/ as a C precursor. A doping concentration as high as 2/spl times/10/sup 19/ cm/sup -3/ has been reached for as-grown (non-annealed) samples. Photoluminescence measurements have been employed to obtain and compare the non-radiative lifetimes in C- and Zn-doped InGaAs. The minority carrier lifetime of as-grown InGaAs:C samples is significantly lower than for as-grown InGaAs:Zn for the same doping concentration. Carrier lifetimes range from 373 ps (p=6.6/spl times/10/sup 16/ cm/sup -3/) to 1.5 ps (p=2.3/spl times/10/sup 19/ cm/sup -3/) in as-grown InGaAs:C, and from 6.8 ns (p=5.0/spl times/10/sup 16/ cm/sup -3/) to 16.8 ps (p=2.1/spl times/10/sup 19/ cm/sup -3/) in InGaAs:Zn, respectively. InGaAs:Zn grown at the same low temperature (450/spl deg/C) as InGaAs:C has a higher minority carrier lifetime. The minority carrier lifetime difference between InGaAs:Zn and InGaAs:C samples is attributed to lower V/III ratio and hydrogen passivation, as well as, lower growth temperatures for the carbon doped InGaAs samples.

Properties of fully self-aligned InAlAs/InGaAs PNP HBTs with very thin bases

For the first time, the effect of base thickness and parasitic collector resistance on InP-based PNP HBTs was determined experimentally. HBTs with 350-/spl Aring/ and 900-/spl Aring/ base layers and self-aligned collector contacts demonstrated DC gain of 21.3 and 5.9, f/sub T/ of 18.6 and 8.5 GHz, and f/sub max/ of 27.3 and 20.8 GHz, respectively. This is the highest f/sub T/ reported for any InP-based PNP HBT. Analysis of these HBTs demonstrated that recombination of holes in the neutral base limited the DC gain, and hole transit across the base was the most significant component of /spl tau//sub ec/. In addition, comparison of HBTs with and without self-aligned collectors demonstrated that collector series resistance had a minor but noticeable impact on f/sub T/ as well as the gain and power-added efficiency at 8 GHz.

New Scanning Photoluminescence Technique for Quantitative Mapping the Surface Recombination Velocity in InP and Related Materials

This paper introduces a new approach, based on room temperature (RT) scanning photoluminescence (SPL) measurements, for non-destructive quantitative mapping of the surface or interface recombination velocity in compound semiconductor structures. The developed technique is validated and applied here to spatially resolved evaluation of the surface recombination velocity of InP substrates and InGaAs(C)/InP heterostructures.

Power-handling capability of W-band InGaAs pin diode switches

The power-handling capability of InGaAs pin diodes is reported and compared to that of GaAs pin diodes. The trade-off between power handling, high frequency performance, and bias conditions is considered. W-band InGaAs pin diode monolithic switches were fabricated using coplanar-waveguide technology, and their large-signal characteristics measured using a W-band load-pull characterization system are reported for the first time.

First demonstration of monolithic InP-based HBT amplifier with PNP active load

An InP-based integrated HBT amplifier with PNP active load was demonstrated for the first time using complementary HBT technology (CRBT). Selective molecular beam epitaxy (MBE) regrowth was employed and a merged processing technology was developed for the monolithic integration of InP-based NPN and PNP HBTs on the same chip. The availability of PNP devices allowed design of high gain amplifiers with low power supply voltage. The measured amplifier with PNP HBT active load achieved a voltage gain of 100 with a power supply (V/sub CC/) of 1.5 V. The corresponding voltage swing was 0.9 V to 0.2 V. The amplifier also demonstrated S/sub 21/ of 7.8 dB with an associated S/sub 11/ and S/sub 22/ of -9.5 dB and -8.1 dB, respectively, at 10 GHz.

A Ka-band monolithic low phase noise coplanar waveguide oscillator using InAlAs/InGaAs HBT☆

A Ka-band oscillator has been designed, fabricated and tested using InAlAs/InGaAs HBTs. Coplanar waveguide technology has been employed to improve the Q-factor of the circuit. An output power of 2.6 dBm with DC to RF conversion efficiency of 7.8% was measured at 31.7 GHz. Low phase noise of � 87 and � 112 dBc/Hz were achieved at an offset frequency of 100 kHz and 1 MHz respectively. These low phase noise values can be attributed to the low 1=f noise of the InAlAs/InGaAs HBT devices and the coplanar design used for the circuit. 2002 Elsevier Science Ltd. All rights reserved.

DC and High Frequency Characterization of Metalorganic Chemical Vapor Deposition (MOCVD) Grown InP/InGaAs PNP Heterojunction Bipolar Transistor

InP/InGaAs PNP heterojunction bipolar transistor (HBT) layers have been grown by metalorganic chemical vapor deposition (MOCVD) and devices have been fabricated using a self-aligned processing technology. A zinc-doped InP layer has been employed as the wide-bandgap emitter layer for the PNP HBT. The base layer used a 500 A thick n-type InGaAs layer doped at 5×1018 cm-3. Successful high frequency operation of these devices has been demonstrated. A single-emitter 1×20 µm2 MOCVD-grown PNP InP/InGaAs HBT achieved current gain cutoff frequency (fT) of more than 11 GHz at a current density (JC) of 8.25×104 A/cm2.

Technology and First Electrical Characteristics of Complementary NPN and PNP InAlAs/InGaAs Heterojunction Bipolar Transistors

A selective molecular beam epitaxy (MBE) regrowth approach is presented and applied in the demonstration of complementary InP heterojunction bipolar transistor (HBT) technology for monolithic integration of NPN and PNP HBTs. State-of-art performance has been observed: The DC gain was 35 for both integrated NPN and PNP HBTs. fT of 79.6 GHz and fmax of 109 GHz were achieved for NPN devices while fT of 11.6 GHz and fmax of 22.6 GHz were achieved for PNP devices. Little performance degradation has been observed compared with same design NPN or PNP HBT layers grown on individual substrates. Monolithic microwave integrated circuits (MMICs) based on complementary InP HBT technology have been studied for the first time using this technology and their electrical characteristics are presented.