GaInP/GaAs HBTs for high-speed integrated circuit applications

The use of GaInP/GaAs heterojunction bipolar transistors (HBTs) for integrated circuit applications is demonstrated. The discrete devices fabricated showed excellent DC characteristics with low V_ce offset voltage and very low temperature sensitivity of the current gain. For a non-self-aligned device with a 3-μm×1.4-μm emitter area, f_T was extrapolated to 45 GHz and f_max was extrapolated to 70 GHz. The measured 1/f noise level was 20 dB better than that of AlGaAs HBTs and comparable to that of low-noise silicon bipolar junction transistors, and the noise bump (Lorentzian component) was not observed. The fabricated gain block circuits showed 8.5 dB gain with a 3-dB bandwidth of 12 GHz, and static frequency dividers (divide by 4) were operable up to 8 GHz     

High-speed, high-current-gain p-n-p InP/InGaAs heterojunctionbipolar transistors

p-n-p InP/InGaAs heterojunction bipolar transistors (HBTs) are reported for the first time. The transistors, grown by metal organic molecular beam epitaxy (MOMBE), exhibited maximum DC current gain values up to 420 for a base doping level of 4×10¹⁸ cm^-3 . Small-signal measurements on self-aligned transistors with 3-μm×8-μm emitter area indicated the unity gain cutoff frequency value of 10.5 GHz and the inferred maximum frequency of oscillation of 25 GHz. The results clearly demonstrate the feasibility of complementary integrated circuits in the InP material system     

AlGaAs/GaAs HBTs for 10-Gb/s ICs using a new base ohmic contactfabrication process

A new basic ohmic contact technology for AlGaAs/GaAs heterojunction bipolar transistors (HBTs) is presented. The effect of the device parameters on the high-frequency performance of HBT ICs for 10-Gb/s systems is analyzed, and it is shown that, at a cutoff frequency (f_T) of 40 GHz or more, reducing base resistance or collector capacitance is more effective than increasing f_T for obtaining high-frequency performance. A process is developed for fabricating base electrodes with a very low ohmic contact resistivity, ~10^-7 Ω-cm², by using a AuZn/Mo/Au alloy, which provides the required high performance. Self-aligned AlGaAs/GaAs HBTs, with a 2.5-μm×5-μm emitter, using a AuZn/Mo/Au alloy base metal and an undoped GaAs collector, are shown to have an f_T and a maximum oscillation frequency of about 45 and 70 GHz, respectively, at 3.5 mA. An AGC amplifier with a 20-dB gain and a bandwidth of 13.7 GHz demonstrates stable performance     

High/fmax collector-up AlGaAs/GaAsheterojunction bipolar transistors with a heavily carbon-doped basefabricated using oxygen-ion implantation

AlGaAs/GaAs collector-up heterojunction bipolar transistors (HBTs) with a heavily carbon-doped base layer were fabricated using oxygen-ion implantation and zinc diffusion. The high resistivity of the oxygen-ion-implanted AlGaAs layer in the external emitter region effectively suppressed electron injection from the emitter, allowing collector current densities to reach values above 10⁵ A/cm ². For a transistor with a 2-μm×10-μm collector, f_T was 70 GHz and f_max was as high as 128 GHz. It was demonstrated by on-wafer measurements that the first power performance of collector-up HBTs resulted in a maximum power-added efficiency of as high as 63.4% at 3 GHz     

Near-ideal I-V characteristics of GaInP/GaAsheterojunction bipolar transistors

GaInP/GaAs heterojunction bipolar transistors (HBTs) have been fabricated and these devices exhibit near-ideal I-V characteristics with very small magnitudes of the base-emitter junction space-charge recombination current. Measured current gains in both 6-μm×6-μm and 100-μm×100-μm devices remain constant for five decades of collector current and are greater than unity at ultrasmall current densities on the order of 1×10^-6 A/cm². For the 6-μm×6-μm device, the current gain reaches a high value of 190 at higher current levels. These device characteristics are also compared to published data of an abrupt AlGaAs/GaAs HBT having a base layer with similar doping level and thickness     

高性能六边形发射极InGaP/GaAs异质结双极型晶体管

六边形发射极的自对准InGaP/GaAs异质结具有优异的直流和微波性能.采用发射极面积为2μm×10μm的异质结双极型晶体管,VCE偏移电压小于150mV,膝点电压为0.5V(IC=16mA),BVCEO大于9V,BVCBO大于14V,特征频率高达92GHz,最高振荡频率达到105GHz.这些优异的性能预示着InGaP/GaAs HBT在超高速数字电路和微波功率放大领域具有广阔的应用前景.     

Experimental values for the hole diffusion coefficient andcollector transit velocity in P-n-p AlGaAs/GaAs HBTs

The diffusion coefficient (D_h) and a value for the collector velocity (v_h) of holes in AlGaAs/GaAs P-n-p HBTs (heterojunction bipolar transistors) were obtained from high-frequency measurements on structures with different base and collector widths. Quantities for D_h and v _h of 5.6 cm²/s and 5.5×10⁶ cm/s, respectively, were obtained by plotting the total emitter-collector delay versus inverse emitter current and extrapolating the data to infinite emitter current to obtain the base and collector transit delays. An f_t and f_max as high as 15 and 29 GHz, respectively, were obtained for non-self-aligned (1-μm emitter mesa/base contact separation) devices with a 2.6-μm×10-μm emitter     

微空气桥隔离的自对准AlGaAs/GaAs异质结双极晶体管

利用微空气桥隔离和自对准技术成功地研制出了自对准结构的AlGaAs/GaAs异质结双极晶体管.器件展现出良好的直流和高频特性.对于发射极面积为2μm×15μm的器件,直流电流增益大于10,失调电压(Offsetvoltage)200mV;电流增益截止频率f_T大于30GHz,最高振荡频率f_max约为50GHz.     

InGaAs/InAlAs/InP collector-up microwave heterojunction bipolartransistors

Collector-up InGaAs/InAlAs/InP heterojunction bipolar transistors (HBTs) were successfully fabricated, and their DC and microwave characteristics measured. High collector current density operation (J_c>30 kA/cm²) and high base-emitter junction saturation current density (J₀>10^-7 A/cm²) were achieved. A cutoff frequency of f _t=24 GHz and a maximum frequency of oscillation f _max=20 GHz at a collector current density of J₀ =23 kA/cm² were achieved on a nominal 5-μm×10-μm device     

High-performance, graded-base AlGaAs/InGaAs collector-upheterojunction bipolar transistors using a novel selective area regrowthprocess

Graded-base AlGaAs/InGaAs collector-up heterojunction bipolar transistors (C-up HBTs) were successfully fabricated using a novel selective area regrowth process to reduce the base resistance and their dc and microwave performances were evaluated. The base is compositionally graded to provide a quasi-built-in field which decreases the base transit time for high-frequency response and increases the base transport factor at low-temperature operation. A unity-gain cutoff frequency f_T=55 GHz and a maximum frequency of oscillation f _MAX=74 GHz for the C-up n-p-n HBT, and an f_T=48 GHz and an f_MAX= 39 GHz for the C-up p-n-p HBT were obtained for devices with a 5-μm×10-μm collector area. The nonself-aligned C-up HBT's reported here show great promise for future high-speed C-up complementary bipolar IC's     

A 6-GHz integrated phase-locked loop using AlGaAs/GaAsheterojunction bipolar transistors

A fully integrated 6-GHz phase-locked-loop (PLL) fabricated using AlGaAs/GaAs heterojunction bipolar transistors (HBTs) is described. The PLL is intended for use in multigigabit-per-second clock recovery circuits for fiber-optic communication systems. The PLL circuit consists of a frequency quadrupling ring voltage-controlled oscillator (VCO), a balanced phase detector, and a lag-lead loop filter. The closed-loop bandwidth is approximately 150 MHz. The tracking range was measured to be greater than 750 MHz at zero steady-state phase error. The nonaided acquisition range is approximately 300 MHz. This circuit is the first monolithic HBT PLL and is the fastest yet reported using a digital output VCO. The minimum emitter area was 3 μm×10 μm with f_t=22 GHz and f_max=30 GHz for a bias current of 2 mA. The speed of the PLL can be doubled by using 1-μm×10-μm emitters in next-generation circuits. The chip occupies a die area of 2-mm×3-mm and dissipates 800 mW with a supply voltage of -8 V     

A new self-alignment technology using bridged base electrode forsmall-scaled AlGaAs/GaAs HBT's

The fabrication and characterization of a new self-aligned HBT utilizing bridged base-electrode technology (BBT) are presented. This new technology simplifies the fabrication process and relaxes the limitations in device size scaling, thus decreasing the emitter size to 1 μm×1 μm. In spite of a large junction periphery area ratio, a good current gain of more than 10 is obtained in an HBT with an emitter size of 1 μm×1 μm. A series of fabricated HBTs shows excellent high-speed performance. The highest values of f_T =90 GHz and f_max=63 GHz are obtained in an HBT with an emitter size of 1 μm×5 μm. The realization of HBTs with small emitters and excellent high-frequency characteristics demonstrates the effectiveness of this new technology     

Microwave operation of high power InGaP/GaAs heterojunction bipolar transistors

The first high power demonstration of an InGaP/GaAs heterojunction bipolar transistor is presented. Multifinger selfaligned HBTs were tested at 3 GHz. A maximum output power of 2.82 W CW was obtained for a 600 mu m/sup 2/ emitter area device (4.7 mW/ mu m/sup 2/ power density) with an attendant gain of 6.92 dB; simultaneously, the device exhibited 55.2% power added efficiency, 69.1% collector efficiency and 8.0*10/sup 4/ A/cm/sup 2/ emitter current density.<>     

Extrinsic base surface passivation in GaInP/GaAs heterojunctionbipolar transistors

The authors demonstrate excellent passivation of the extrinsic base surfaces in GaInP/GaAs heterojunction bipolar transistors (HBTs) having small emitter areas. Passivated devices with an area as small as 4×20 μm² exhibit the highest reported current gain value of 2690 for GaInP/GaAs HBTs, while unpassivated 4×20-μm ² devices exhibit a current gain of only 500. Measured current gains as a function of collector current density are almost identical for devices with varying emitter widths of 4, 6, 8, 12, 16, and 100 μm. The current gains are also nearly identical for devices with varying passivation ledge widths of 1, 2, 3, and 6 μm. These results are contrasted with those of a previously published study reporting surface passivation for a GaInP/GaAs HBT with a large emitter area     

Very high-power-density CW operation of GaAs/AlGaAs microwaveheterojunction bipolar transistors

Thermal instability of multi-emitter high-power microwave heterojunction bipolar transistors (HBTs) was eliminated using a novel heat spreading technique that regulates internal device currents to avoid the formation of hot spots. Devices with 2- and 3-μm minimum emitter sizes and no intentional ballast resistors showed unconditionally stable CW operation up to the device electronic limitations. A record 10-mW/μm² power density was obtained at 10 GHz with 7-dB gain and 60% power-added efficiency. The highest efficiency was 67.2% at 9.3-mW/μm² power density. It was shown that stable high-power-density operation can be maintained at multiwatt output power levels     

S波段0.3W AlGaAs/GaAs HBT功率管

采用标准的湿法刻蚀工艺研制出了S波段工作的非自对准AlGaAs/GaAs异质结双极晶体管．对于总面积为8×2μm×10μm的HBT器件,测得其直流电流增益大于10,电流增益截止频率fT大于20GHz,最高振荡频率fmax大于30GHz．连续波功率输出为0.3W,峰值功率附加效率41％．     

Significant operating voltage reduction on high-speed GaAs-based heterojunction bipolar transistors using a low band gap InGaAsN base layer

We report the fabrication of double heterojunction bipolar transistors (DHBTs) with the use of a new quaternary InGaAsN material system that takes advantage of a low-energy band gap E/sub G/ in the base to reduce operating voltages in GaAs-based electronic devices. InGaP/In/sub 0.03/Ga/sub 0.97/As/sub 0.99/N/sub 0.01//GaAs DHBTs with improved band gap engineering at both heterojunctions exhibit a DC peak current gain over 16 with small active emitter area. The use of the lattice-matched In/sub 0.03/Ga/sub 0.97/As/sub 0.99/N/sub 0.01/ (E/sub G/=1.20 eV) base layer allows a significant reduction of the turn-on voltage by 250 mV over standard InGaP/GaAs HBTs, while attaining good high-frequency characteristics with cutoff frequency and maximum oscillation frequency as high as 40 GHz and 72 GHz, respectively. Despite inherent transport limitations at the present time, which penalize peak frequencies, this novel technology provides comparable RF performance to conventional devices with a GaAs control base layer but at much lower operating base-emitter bias conditions. This technical progress should benefit to the next generation of RF circuits using GaAs-based HBTs with lower power consumption and better handling of supply voltages in battery-operated wireless handsets.     

High performance Al0.35Ga0.65As/GaAs HBT's

AlGaAs emitter heterojunction bipolar transistors (HBTs) are demonstrated to have excellent dc and RF properties comparable to InGaP/GaAs HBTs by increasing the Al composition. Al_0.35Ga _0.65As/GaAs HBTs exhibit very high dc current gain at all bias levels, exceeding 140 at 25 A/cm² and reaching a maximum of 210 at 26 kA/cm² (L=1.4 μm×3 μm, R_sb=330 Ω/□). The temperature dependence of the peak dc current gain is also significantly improved by increasing the AlGaAs mole fraction of the emitter. Device analysis suggests that a larger emitter energy gap contributes to the improved device performance by both lowering space charge recombination and increasing the barrier to reverse hole injection     

Metamorphic InP/InGaAs heterojunction bipolar transistors on GaAssubstrate: DC and microwave performances

High-performance InP/In_0.53Ga_0.47As metamorphic heterojunction bipolar transistors (MHBTs) on GaAs substrate have been fabricated using In_xGa_1-xP strain relief buffer layer grown by solid-source molecular beam epitaxy (SSMBE). The MHBTs exhibited a dc current gain over 100, a unity current gain cutoff frequency (f_T) of 48 GHz and a maximum oscillation frequency (f_MAX) of 42 GHz with low junction leakage current and high breakdown voltages. It has also been shown that the MHBTs have achieved a minimum noise figure of 2 dB at 2 GHz (devices with 5×5 μm ² emitter) and a maximum output power of 18 dBm at 2.5 GHz (devices with 5×20 μm² emitter), which are comparable to the values reported on the lattice-matched HBTs (LHBTs). The dc and microwave characteristics show the great potential of the InP/InGaAs MHBTs on GaAs substrate for high-frequency and high-speed applications     

Submicron-square emitter AlGaAs/GaAs HBTs with AlGaAshetero-guardring

Successful operation of submicron-square emitter AlGaAs/GaAs HBTs is demonstrated for the first time by using a fully mesa-structure-type emitter-base junction-area definition method with an AlGaAs hetero-guardring. The hetero-guardring reduces surface recombination current at the emitter-mesa edge to 1.4 μA/μm. This is 1/10 of that for devices without the guardring. Here, dc gains of 20, 26, and 40 are achieved for 0.5 μm×0.5 μm, 0.7 μm×0.7 μm, and 0.9 μm×0.9 μm emitter HBTs, respectively. An f_T of 40 GHz, and an f_max of 30 GHz are obtained for 0.9 μm×0.9 μm at a J_C of 1.0×10⁵ A/cm²