摘要:

Effectiveness ofinsituprocessing, which combines Cl2gas etching with subsequent molecular beam epitaxy regrowth in an ultrahigh vacuum environment, is quantitatively evaluated with nonradiative carrier recombination velocity,S, of etched/regrown AlGaAs/GaAs heterointerfaces. When AlGaAs isinsituregrown on Cl2gas‐etched flat GaAs surface, theSvalue is as low as 1.3×103cm/s. This value is lower than that of air‐exposed/regrown (orexsituprocessed) interfaces, thus representing the essential superiority ofinsituprocessing overexsitu. Buried GaAs/AlGaAs multiquantum‐well (MQW) mesa‐stripes are also fabricated byinsituCl2gas‐etching/regrowth. TheSvalue at the MQW mesa‐sidewall regrown with AlGaAs is 6.0×103cm/s, which is reduced by more than one order of magnitude from that of a nonburied case.

ISSN:0734-211X    

DOI:10.1116/1.588742

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

Etch‐mask thin‐film material that is particulate‐free and topographically smooth has been created from a standard photoresist spun onto standard semiconductor substrates such as gallium arsenide, indium phosphide, and silicon, and then pyrolyzed by exposing to a temperature of 300 °C in air atmosphere for 1 min on a standard laboratory hot‐plate. The resulting pyrolytic‐photoresist thin‐film is chemically inert to many standard organic solvents including the solvent of photoresist itself and to many inorganic reagents used in semiconductor processing. Therefore the pyrolytic‐photoresist can be patterned by sulfur hexafluoride reactive ion etching via a standard photoresist mask. Upon stripping the standard photoresist in a mixture of 1:1/acetone:developer agitated ultrasonically, the remaining patterned pyrolytic‐photoresist performs as an excellent etch‐mask in chemically assisted ion beam etching and reactive ion etching systems. Thus it can be a key material in the multilayer masking technique used to sculpt self‐aligned three‐dimensional microstructures with deep and smooth facets which are needed for example for photonic integrated circuits and micro‐electro‐mechanical systems.

ISSN:0734-211X    

DOI:10.1116/1.588743

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

A study of the effects of reactive ion etching (RIE) on molecular beam epitaxy‐grown Zn1−xCdxSe/ZnSe strained multiple quantum well samples using low temperature photoluminescence reveals a blueshift in the characteristic peak positions of the wells when etched with CH4/H2. Based on the experimental results, we suggest that the blueshift is not a result of hydrogen incorporation, but that etch induced damage relaxes the compressive strain present in the as‐grown quantum well, producing the observed blueshift. After thermal annealing the energy of the photoluminescence signal returns to its original value, suggesting a restoration of the strain by elimination of the structural damage induced by RIE. However, the original photoluminescence intensity is not recovered by annealing.

ISSN:0734-211X    

DOI:10.1116/1.588744

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

Dry etching using ions can cause damage to the underlying semiconductor. This paper discusses damage in III–V semiconductors and presents examples of etching conditions under which it can be effectively eliminated. A distinction between surface and sidewall damage is made and methods of measuring both parameters are reviewed. It is noted that the noble gases cause relatively deep damage, while under the correct circumstances, etchants that have a marked chemical effect can cause much less damage. The present state of understanding of the mechanisms for the damage is discussed.

ISSN:0734-211X    

DOI:10.1116/1.588745

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

In‐plane gated (IPG) quantum wire transistors were fabricated using dry etching in a Cl2/Ar plasma generated with an electron cyclotron resonance source. The electrical characteristics of the IPG transistors were correlated with the geometrical dimensions as well as the dry etching and passivation conditions. In‐plane gates with the width of the channel (Wc) and the width of the gate isolation (Wg) ranging from 100 to 850 nm were studied. Good field‐effect transistor characteristics with transconductances up to 371 mS/mm were obtained on these devices. At a gate‐source voltage (VGS) of 2 V, the saturated drain‐source current (IDSAT) increased from 68 to 153 μA asWcincreased from 440 to 800 nm. No current was measured on IPG transistors withWc ≤−130 nm. The quasi‐one‐dimensional channel can be completely pinched off withVGS ≤−1 V. It was found that the gate leakage current decreased with a widerWgand a deeper depth for the gate isolation. The leakage current atVGS=2 V decreased significantly from 250 to<0.1 pA when the etch depth increased from 320 to 440 nm. The gate leakage current andIDSwere also found to increase with rf power used for etching due to additional defects generated at higher ion energy. These defects, however, can be passivated with low energy chlorine species, and reduction of the gate leakage current from 40 to 4.4 nA was observed after a 1 min Cl2plasma passivation.

ISSN:0734-211X    

DOI:10.1116/1.588746

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

The effects of the addition of a small amount of O2to SiCl4/SiF4plasma and the thickness of the GaAs capping layer on gate recess etching of GaAs pseudomorphic high electron mobility transistor (p‐HEMT) devices have been studied. During gate recessing of GaAs/AlGaAsp‐HEMTs using a selective reactive ion etching (RIE) process in SiCl4/SiF4plasma [see S. K. Murad, N. I. Cameron, P. D. Wang, S. P. Beaumont, and C. D. W. Wilkinson, Microelectron. Eng.27, 439 (1995)], it was found that the profile of the gate changes dramatically from undercut to nearly vertical with no lateral etching when the thickness of the capping layer was reduced below 40 nm. This vertical profile puts the gate metal too close to the recess edges in devices with a ≤30 nm capping layer. The addition of a very small amount of O2to SiCl4/SiF4plasma was seen to increase GaAs etch rates remarkably, while maintaining the high selectivity over AlGaAs. This increase in the etch rate agrees well with optical emission spectroscopic observations which indicate that the Cl emission has increased by more than an order of magnitude for the addition of only 1.5% of O2to SiCl4/SiF4plasma. This selective RIE process of SiCl4/SiF4/O2was applied to gate recess etching of GaAs/AlGaAs/InGaAsp‐HEMTs with various capping layer thicknesses. The profile of theTgates changed from nearly vertical (with no undercut or gate offset) to undercut with a lateral etch rate depending on the thickness of the capping layer. The lateral etching rate also strongly depends on the O2flow. Thep‐HEMT devices gate recessed using this process (SiCl4/SiF4/O2) exhibited anftof 120 GHz,gmof 700 mS/mm and a gain of 9.5 dB at 94 GHz.

ISSN:0734-211X    

DOI:10.1116/1.588747

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

In this work, we study the hydrogen introduced into InP during methane/hydrogen/argon reactive ion etching (RIE) to determine its effect on metalorganic chemical vapor deposition regrowth. We replace hydrogen with deuterium and confirm that deuterium is introduced into the substrate during methane/deuterium/argon RIE with secondary ion mass spectrometry. During regrowth, the deuterium diffuses from deep within the material and clusters at the regrowth interface, strongly indicating the presence of defects. To further understand the role of hydrogen, we investigate the separate effects of ion damage and hydrogenation on subsequent regrowth. We find that photoluminescence of regrown quantum wells is greatly improved on argon ion damaged substrates which have been additionally exposed to hydrogen at −150 V for 3 min. These experiments illustrate that hydrogen interacts with defects in InP, preventing their propagation during regrowth, and improving the photoluminescence quality of regrown quantum wells.

ISSN:0734-211X    

DOI:10.1116/1.588748

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

The effect of CH4/H2reactive ion etching on In0.52Al0.48As surfaces and In0.52Al0.48As/ In0.53Ga0.47As/InP heterostructure have been studied using Schottky diode, x‐ray photoelectron spectroscopy, and room temperature transport experiments. The application of CH4/H2as a dry etch gas for the gate recess step in the fabrication of 0.2 μm T‐gate In0.52Al0.48As/In0.53Ga0.47As/InP high electron mobility transistor has been explored. We show that while the room temperature mobility and the dc and high frequency performance of the dry etched devices are at least comparable to the wet etched ones, their microwave noise behaviours are extremely sensitive to dry etch‐induced defects.

ISSN:0734-211X    

DOI:10.1116/1.588749

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

We have investigated the radiation enhanced diffusion of ion defects during reactive ion beam etching of GaAs and InP, using the multiple quantum well (MQW) probe technique. During low energy (sub‐keV) Ar+ion exposure, illumination with light of energy above the band gap can substantially reduce the photoluminescence efficiency of MQW samples, relative to those which were not laser illuminated; the degradation of luminescence efficiency increases with the intensity of the light. Illumination with light of energy below the band gap produces a slight increase in the damage profiles. The observation of enhanced defect diffusion due to optical radiation in our studies suggests that in ion‐assisted etching of semiconductors, the generation of excess electron‐hole pairs and their subsequent recombination can play an important role in the propagation of defects into the substrate.

ISSN:0734-211X    

DOI:10.1116/1.588750

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

We investigated the suppression of the charge buildup caused by the electron shading effect using a counter rf bias, which produces high energy electrons reflected from the counter electrode. We expected that these high energy electrons could overcome the potential barrier formed at the entrance of high aspect‐ratio hole patterns and to decrease the charge buildup at the bottom of these patterns. We directly investigated the charge buildup by measuring dc self‐bias potential differences between high aspect‐ratio hole patterns and open‐space pattern. The dc self‐bias potential difference increased, independent of the hole pattern aspect ratio, at the lower substrate rf bias voltage and they tended to saturate at the following higher substrate rf bias voltage. The dc self‐bias potential difference reached about 100 V with a substrate rf bias voltage of 400 V for an aspect ratio of 2. The dc self‐bias potential difference dramatically decreased from 100 to 20 V by increasing the counter rf bias voltage. In addition, we investigated this suppression effect by changing the phase difference between counter and substrate bias voltages when both bias frequencies were set to 13.56 MHz. We found that there is a variation of the suppression effect with respect to the phase difference. This indicates that high energy electrons, which were accelerated in an oscillation sheath, could reach the bottom of the holes.

ISSN:0734-211X    

DOI:10.1116/1.588648

出版商:American Vacuum Society    

年代:1996

数据来源: AIP