Showing papers by "Evelyn L. Hu published in 1990"
TL;DR: In this article, a superconductor-semiconductor weak link was constructed using an InAs−AlSb quantum well as the channel between Nb electrodes, which yielded a superconducting coherence length (3700 A) inside the channel.
Abstract: We have constructed a superconductor‐semiconductor weak link using an InAs‐AlSb quantum well as the channel between Nb electrodes. The structure draws on (a) the barrier‐free nature of the Nb‐InAs interfaces and (b) the combination of high electron concentrations and very high electron mobilities in the InAs wells, which yield a large superconducting coherence length (3700 A) inside the channel. A large (lineal) critical supercurrent density of 32 mA/mm was obtained at 1.4 K, for a channel length of 0.6 μm. After temporary exposure to a magnetic field, the current‐voltage characteristic became hysteretic, with an increase in critical current density to 132 mA/mm. The latter value corresponds to an areal current density of 8.8×105 A/cm2.
46 citations
TL;DR: In this article, both the thermally activated and remote plasma activated etching reactions between Cl2 and HCl gases and GaAs and InP substrates were characterized, and the etch rate versus temperature behavior was similar to the plasma off case.
Abstract: Both the thermally activated and remote plasma activated etching reactions between Cl2 and HCl gases and GaAs and InP substrates are characterized. Though GaAs etches nearly three times faster in Cl2 with a remote plasma operating, the etch rate versus temperature behavior is similar to the plasma‐off case. Significant etch rates of GaAs are observed for HCl remotely generated plasma even at room temperature (∼1500 A/min). InP etching in HCl or Cl2 shows a weak temperature dependence for T>150 °C but changes rapidly below this temperature (EA∼55±15 kcal/mole).
35 citations
TL;DR: In this article, a planar heterostructure field effect transistors with InAs quantum well channels and AlSb barrier layers were fabricated and a 1.5 μm gate device had a room temperature extrinsic transconductance of 208 mS/mm.
Abstract: We have fabricated planar heterostructure field‐effect transistors with InAs quantum well channels and AlSb barrier layers. Argon implantation was used to form a damaged layer, which resulted in partial device to device isolation. A 1.5 μm gate device had a room‐temperature extrinsic transconductance of 208 mS/mm.
25 citations
TL;DR: In this article, the etch rate versus temperature data for GaAs and InP etched by Cl2 and HCl both with and without a remote plasma were presented, and the data were described both qualitatively and quantitatively by a thermodynamic model utilizing reactant-flux-limited and product-desorption-limited regimes.
Abstract: This work presents etch rate versus temperature data for GaAs and InP etched by Cl2 and HCl both with and without a remote plasma. The data is described both qualitatively and quantitatively by a thermodynamic model utilizing reactant‐flux‐limited and product‐desorption‐limited regimes. This ‘‘ionless’’ etching technique demonstrates reactant‐flux‐limited, temperature‐independent behavior for HCl etching of GaAs for over five orders of magnitude of flux. InP and GaAs show nearly equirate etching at T>150 °C with both gases. Reactive ion etching (RIE) with Cl2 of InP at elevated temperatures produces only moderate rate enhancements; RIE gave a maximum etch rate of ∼800 A/min at 175 °C compared to ∼0.5 μm/min obtained with the remote plasma system at the same temperature.
24 citations
TL;DR: In this paper, a self-aligned Si-Zn diffusion from which both optical and electrical confinements are obtained simultaneously has been used for the fabrication of IILD laser structures.
Abstract: Stripe geometry lasers defined by impurity‐induced layer disordering (IILD) have been fabricated utilizing a novel technology of self‐aligned Si‐Zn diffusion from which both optical and electrical confinements are obtained simultaneously. The fabrication process is considerably simpler than that for the conventional IILD lasers and the parasitic p‐n junction area in the laser structures is minimized. Typical lasers with threshold current Ith=5.2 mA and differential quantum efficiency ηd=81% at room‐temperature continuous operation as well as highly uniform yield ≳80% have been obtained.
18 citations
TL;DR: In this article, the authors reported the first report of deposition of a III-V semiconductor on a superconductor, without significant degradation of Tc. The InAs was grown by molecular beam migrationenhanced epitaxy at a substrate temperature of 250 °C and the Tc(zero) of the Tl film before and after InAs deposition was 106 and 100 K, respectively.
Abstract: Results of growth of InAs on a superconducting TlCaBaCuO (2‐1‐2‐2) thin film are reported. The InAs was grown by molecular beam migration‐enhanced epitaxy at a substrate temperature of 250 °C. The Tc(zero) of the Tl film before and after InAs deposition was 106 and 100 K, respectively. X‐ray diffraction and reflection electron microscopy studies showed the InAs to be polycrystalline, having grains in the 300 A size range. This is the first report of deposition of a III‐V semiconductor on superconductor, without significant degradation of Tc.
16 citations
TL;DR: In this paper, superconducting YBaCuO (1 2 3 ) thin films have been deposited on GaAs by laser ablation, in the presence of an oxygen plasma, at a substrate temperature of 600 °C The (100) GaAs had a thin (100 A) Al03Ga07As cap layer, in order to prevent decomposition of the GaAs.
Abstract: Superconducting YBaCuO (1‐2‐3) thin films have been deposited on GaAs by laser ablation, in the presence of an oxygen plasma, at a substrate temperature of 600 °C The (100) GaAs had a thin (100 A) Al03Ga07As cap layer, in order to prevent decomposition of the GaAs The as‐deposited YBaCuO film had a Tc (onset) of 80 K and a Tc (zero) of 20 K Transmission electron microscopy studies showed the presence of voids in the GaAs, ∼1000 A in length, and extending 500 A into the GaAs
15 citations
23 Apr 1990
TL;DR: In this paper, an attempt is made to add insight into the expectation that in the dry etching of InP, increased temperatures should assist etching even in ion enhanced systems, both in regard to rate and profile.
Abstract: An attempt is made to add insight into the expectation that in the dry etching of InP, increased temperatures should assist etching even in ion enhanced systems, both in regard to rate and profile. Results for InP and GaAs are compared with each other and results in the literature. At >150 degrees C, the InP etch rate is approximately twice as fast with the plasma on as with the plasma off. The rapid etch rate in molecular Cl/sub 2/ alone, i.e. with the plasma off, confirms that plasma generated radicals are not necessary for etching to occur. This is also observed for GaAs etching in Cl/sub 2/. Thus, molecular Cl/sub 2/ can crack on the surface to form the etch products. At lower temperatures the etch rate enhancement with the plasma on is not as apparent, and a much larger scatter in the data is observed. >
1 citations