Suppression of Beryllium Diffusion by Incorporating Indium in AlGaAs for HBT Applications using Molecular Beam Epitaxy

Abstract

We developed a molecular beam epitaxy technique to suppress Be diffusion by incorporating In in the AlGaAs epilayer. Diffusion coefficients of Be-doped In y (Al0.1Ga0.9)1-y As (p: 7×1019 cm-3) grown at 600°C were reduced from 1×10-14 cm2/s to 2×10-15 cm2/s when the InAs mole fraction y was increased from 0 to 0.07, indicating that compressive stress in the epilayer caused by incorporating In plays an important role in suppressing Be diffusion. We fabricated a heterojunction bipolar transistor with a 100-nm-thick p+-In0.055(Al x Ga1-x )0.945As base layer (x: 0 to 0.1), and obtained a DC current gain of 27.

A study of Be diffusion in InGaAsP layers grown by gas-source molecular beam epitaxy

“…GaAs [8] Above 1 × 10 19 800 3.5 × 10 −14 GaAs [11] 2 × 10 18 725 4.0 × 10 −16 GaAs [11] 2 × 10 18 825 2.3 × 10 −15 GaAs [9] 3 × 10 19 900 5-10 × 10 −14 GaAs [7] 1 × 10 19 700 8.0 × 10 −15 In 0.53 Ga 0.47 As [22] 3 × 10 19 800 9.83 × 10 −12 In 0.53 Ga 0.47 As [19] Above 5 × 10 16 680 (1.9 ± 0.6) × 10 −15 Al 0.1 Ga 0.9 As [18] 7 × 10 19 600 1.0 × 10 −14 In 0.07 (Al 0.1 Ga 0.9 ) 0.93 As [18] In this way, if substitutional Be concentrations are higher than C crit in s , the local self-interstitial concentration C I in the in-diffusion region can be reduced to its thermal equilibrium value C eq I (p) [13]. This effect could be explained by considering the sufficiently high oversaturation of self-interstitial species in the diffusion-front region (see figure 6).…”

“…Be (and Zn) diffusion in GaAs has been studied extensively in the past [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]; however, little previous work on Be diffusion in the other binary III-V compounds [10,12], ternary GaAs-based compounds [3,5,10,18,19] and ternary InP-based compounds [20][21][22] has been done.…”

Growth optimization of InAs/GaAs quantum dots and performance enhancement of a GaAs tunnel diode by embedding quantum dots for solar cell application

“…This can in fact cause the dopant atoms of the tunnel junction to diffuse [30], thereby deteriorate the junction doping profile and degrade the solar cell performance. The presence of large amount of beryllium dopants along with interstitial beryllium [50] results in tensile strain at the junction which acts as a driving force for the beryllium atoms to diffuse, however, the resulting tensile strain gets compensated by the compressive strain due to the presence of embedded InAs QD layer. This prevents the downward diffusion of beryllium into the neighboring Si-doped n-GaAs layer, thereby retaining the junction doping profile which was confirmed through secondary ion mass spectrometer measurements (not shown here).…”

Improved performance of GaAs tunnel diode by embedding InAs quantum dot layer for tandem solar cells

“…11) However, for the GaAs TD without an InAs QD layer, the diffusion of beryllium opposite the direction of growth at the p=n junction interface of the GaAs TD was enhanced after annealing, while the diffusion of beryllium for the TD with an InAs QD layer remained almost the same. The reason can be explained as follows: the presence of a high concentration of beryllium induces tensile strain, which is compensated by the compressive strain caused by the InAs QD layer, 20) which reduces beryllium diffusion. Another noteworthy observation is the smaller diffusion length of silicon into the beryllium-doped p-type GaAs layer in the TD with the InAs QD layer as compared with that in which the InAs QD layer is absent.…”